Communication method and device

Abstract

The present application discloses a communication method and apparatus for providing a CHO mechanism when an NTN cell covering geographical areas of multiple countries or service areas of multiple operators is configured as a candidate target cell for a terminal device. The method includes: in a CHO handover scenario, if the first PLMN information and / or first AMF information of the candidate target cell corresponds to the first CHO configuration information and the first area information, and the second PLMN information and / or second AMF information corresponds to the second CHO configuration information and the second area information, then the terminal device can determine the target cell and the target PLMN information and / or the target AMF information based on the first information received from the source network device and the current area of ​​the terminal device, so as to improve the reliability of the handover.

Description

Technical Field

[0001] The present application relates to the field of wireless communication technology, and in particular to a communication method and device. Background Art

[0002] Non-terrestrial networks (NTN) communication systems provide seamless coverage for terminal devices by deploying access network equipment or some of its functions on non-ground devices such as high-altitude platforms or satellites. Since high-altitude platforms or satellites are located at high altitudes, they are less affected by natural disasters. Therefore, NTN communication systems have high reliability.

[0003] A cell in an NTN communication system is called an NTN cell. A key feature of an NTN communication system is that it typically has a relatively large coverage area. For example, a cell coverage diameter can reach tens to thousands of kilometers. Therefore, a single NTN cell may cover geographical areas in multiple countries or service areas of multiple operators. For example, if the NTN system is a satellite communication system, a satellite can indicate that it supports services in multiple countries or operators by broadcasting information about multiple public land mobile networks (PLMNs). Alternatively, a satellite can indicate that it supports services in multiple countries or operators by broadcasting information about multiple access and mobility management functions (AMFs).

[0004] To improve handover reliability, the network configures terminal devices to perform conditional handover (CHO) and configures one or more candidate target cells for the terminal devices. However, there is currently no solution for how CHO should be performed when the network configures an NTN cell that supports multiple PLMNs and / or multiple AMFs as a candidate target cell. Summary of the Invention

[0005] A communication method and apparatus in an embodiment of the present application are used to provide a CHO mechanism when the candidate target cell is an NTN cell supporting multiple PLMNs and / or multiple AMFs, so as to improve the reliability of switching.

[0006] In the first aspect, an embodiment of the present application provides a communication method, which can be executed by a terminal device or by a component (such as a chip or circuit) configured in the terminal device. In the following description of this application, the method executed by a terminal device will be used as an example for illustration.

[0007] The method may include: a terminal device receives first information of a candidate target cell from a source network device, the first information including first PLMN information and / or first AMF information, and second PLMN information and / or second AMF information; wherein the first information also includes first CHO configuration information and first area information corresponding to the first PLMN information and / or first AMF information, and second CHO configuration information and second area information corresponding to the second PLMN information and / or second AMF information, the first area information is used to indicate the first area covered by the candidate target cell, and the second area information is used to indicate the second area covered by the candidate target cell; the terminal device determines the target cell and target PLMN information and / or target AMF information based on the first information and the area where the terminal device is currently located.

[0008] The above technical solution provides a CHO mechanism when cells covering geographical areas of multiple countries or service areas of multiple operators are configured as candidate target cells for a terminal device. Because the terminal device can determine the target cell, target PLMN, and / or target AMF from the configured candidate target cells based on the first information received from the source network device and the region in which it is currently located, the above technical solution can effectively improve the reliability of handover.

[0009] In a possible design of the first aspect, the terminal device determines the target cell and target PLMN information and / or target AMF information based on the first information and the area where the terminal device is currently located, which may specifically include: if the first CHO execution condition in the first CHO configuration information is met and the terminal device is currently located in the first area, the terminal device may determine that the candidate target cell is the target cell, and determine the first PLMN information as the target PLMN information, and / or determine the first AMF information as the target AMF information.

[0010] With the above technical solution, the terminal device can determine the cell, PLMN information and AMF information that match the area where its current location is located among the cells that meet the CHO execution conditions as the target cell, target PLMN information and target AMF information respectively. In this way, it can effectively avoid the problem of CHO switching failure caused by the selected target PLMN and / or target AMF not being the PLMN and / or AMF supported by the area where the terminal device is currently located.

[0011] In a possible design of the first aspect, the terminal device determines the target cell and target PLMN information and / or target AMF information based on the first information and the area where the terminal device is currently located, which may specifically include: if the first CHO execution condition in the first CHO configuration information and the second CHO execution condition in the second CHO configuration information are both met, and the terminal device is currently located in the first area, then the terminal device can determine that the candidate target cell is the target cell, and determine the first PLMN information as the target PLMN information, and / or determine the first AMF information as the target AMF information.

[0012] In the above technical solution, when the CHO execution conditions corresponding to different PLMN information and / or AMF information of the candidate target cell are met, the terminal device can determine the target PLMN and / or target AMF based on the area where the current location is located and the correspondence between the various areas covered by the candidate target cell and the PLMN and / or AMF, thereby avoiding the problem of switching failure.

[0013] In a possible design of the first aspect, the method also includes: the terminal device sends a first message to the target network device, the first message being used to indicate that the terminal device has successfully switched to the target cell, the first message including target PLMN information and / or target AMF information, and the target network device is a network device that manages the target cell.

[0014] In the above technical solution, after the terminal device successfully switches to the target cell, the terminal device can also send a first message to the target network device to indicate that it has successfully switched to the target cell, or in other words, a first message to indicate that the switching is completed, so as to facilitate the target network device to release unnecessary CHO configurations or connections, etc., thereby effectively improving resource utilization.

[0015] In a possible design of the first aspect, the first message also includes identification information of the target cell and index information corresponding to the target cell. In this way, it is convenient for the target network device to determine the target cell to which the terminal device switches.

[0016] In a possible design of the first aspect, when the RACH resource information included in the first CHO configuration information is different from the RACH resource information included in the second CHO configuration information, the first message may be encrypted using a first key corresponding to the first CHO configuration information.

[0017] In a possible design of the first aspect, when the RACH resource information included in the first CHO configuration information is the same as the RACH resource information included in the second CHO configuration information, the terminal device can send two first messages to the target network device, wherein one first message is encrypted using a first key corresponding to the first CHO configuration information, and the other first message is encrypted using a second key corresponding to the second CHO configuration information.

[0018] In the above technical solution, the terminal device can use the key corresponding to the CHO configuration information to encrypt the first message, thereby improving the security of the first message during transmission.

[0019] In a possible design of the first aspect, the first CHO configuration information includes first CHO execution condition information, which is used to indicate the first CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the first PLMN information includes an identifier of the first PLMN, the first AMF information includes an identifier of the first AMF, or includes an identifier of the first AMF and an identifier of the first PLMN; the second CHO configuration information includes second CHO execution condition information, which is used to indicate the second CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the second PLMN information includes an identifier of the second PLMN, the second AMF information includes an identifier of the second AMF, or includes an identifier of the second AMF and an identifier of the second PLMN.

[0020] In a possible design of the first aspect, the method also includes: the terminal device releases the second PLMN information and / or the second AMF information, and releases the second CHO configuration information and the second area information.

[0021] On the second aspect, an embodiment of the present application provides a communication method, which can be executed by a source network device or by a component (such as a chip or circuit) configured in the source network device. In the following description of this application, the source network device will be used as an example to illustrate the execution of this method.

[0022] The method may include: a source network device receives first information of a candidate target cell from a candidate target network device, the first information including first PLMN information and / or first AMF information, and second PLMN information and / or second AMF information; wherein the first information also includes first CHO configuration information and first area information corresponding to the first PLMN information and / or first AMF information, and second CHO configuration information and second area information corresponding to the second PLMN information and / or second AMF information, the first area information is used to indicate a first area covered by the candidate target cell, and the second area information is used to indicate a second area covered by the candidate target cell; the source network device sends the first information of the candidate target cell to the terminal device.

[0023] The above technical solution provides a CHO mechanism when a cell covering a geographical area of ​​multiple countries or a service area of ​​multiple operators is configured as a candidate target cell for a terminal device. If the candidate target cell supports multiple PLMNs and / or AMFs, the source network device can provide the terminal device with CHO configuration information and area information corresponding to each PLMN and / or AMF when performing CHO configuration. This allows the terminal device to select a target cell, target PLMN, and / or target AMF from cells that meet the CHO execution conditions based on its own location, thereby improving handover reliability.

[0024] In a possible design of the second aspect, the first CHO configuration information includes first CHO execution condition information, which is used to indicate the first CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the first PLMN information includes the identifier of the first PLMN, the first AMF information includes the identifier of the first AMF, or includes the identifier of the first AMF and the identifier of the first PLMN; the second CHO configuration information includes second CHO execution condition information, which is used to indicate the second CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the second PLMN information includes the identifier of the second PLMN, the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

[0025] On the third aspect, an embodiment of the present application provides a communication method, which can be executed by a target network device or by a component (such as a chip or circuit) configured on the target network device. In the following description of this application, the target network device will be used as an example to illustrate the execution of this method.

[0026] The method may include: a target network device sends first information of a candidate target cell to a source network device, the first information including first PLMN information and / or first AMF information, and second PLMN information and / or second AMF information; wherein the first information also includes first CHO configuration information and first area information corresponding to the first PLMN information and / or first AMF information, and second CHO configuration information and second area information corresponding to the second PLMN information and / or second AMF information, the first area information is used to indicate a first area covered by the candidate target cell, and the second area information is used to indicate a second area covered by the candidate target cell; if the terminal device determines that the candidate target cell is a target cell, the target network device receives a first message from the terminal device, the first message is used to indicate that the terminal device has successfully switched to the target cell, the first message includes target PLMN information and / or target AMF information, the target PLMN information and / or target AMF information is the first PLMN information and / or first AMF information, or the second PLMN information and / or second AMF information.

[0027] The above technical solution provides a CHO mechanism when a cell covering the geographical areas of multiple countries or the service areas of multiple operators is configured as a candidate target cell for a terminal device. If the candidate target cell supports multiple PLMNs and / or AMFs, the candidate target network device can provide the source network device with CHO configuration information and area information corresponding to each PLMN and / or AMF when preparing for CHO handover. This facilitates the terminal device to determine the target cell, target PLMN, and / or target AMF from cells that meet the CHO execution conditions based on its own location area, thereby improving the reliability of the handover.

[0028] In addition, when the terminal device determines the candidate target cell as the target cell, the target network device can determine the target PLMN and / or target AMF to which the terminal device accesses based on the first message, thereby releasing unnecessary CHO configurations or connections for the terminal device, effectively improving resource utilization.

[0029] In a possible design of the third aspect, when the RACH resource information included in the first CHO configuration information is different from the RACH resource information included in the second CHO configuration information, the target network device may determine a first key for decrypting the first message based on the RACH resource information used by the terminal device to initiate a random access process, and use the first key to decrypt the first message.

[0030] In a possible design of the third aspect, when the RACH resource information included in the first CHO configuration information is the same as the RACH resource information included in the second CHO configuration information, the target network device may receive two first messages from the terminal device and decrypt the two first messages using a first key, and / or decrypt the two first messages using a second key; wherein the first key is a key corresponding to the first CHO configuration information, and the second key is a key corresponding to the second CHO configuration information.

[0031] In the above technical solution, the target network device can decrypt the first message using the key corresponding to the CHO configuration information, thereby obtaining the information contained in the first message. When the RACH resource information included in different CHO configuration information is different, the target network device can determine the key for decrypting the first message based on the RACH resource information used by the terminal device during random access. When the RACH resource information included in different CHO configuration information is the same, since the terminal device has sent multiple first messages encrypted using keys corresponding to different CHO configuration information, the target network device can successfully decrypt the first message using the key corresponding to any CHO configuration information.

[0032] In a possible design of the third aspect, the method also includes: the target network device sends a second message to the target AMF corresponding to the target AMF information, and the second message is used to indicate to the target AMF that the terminal device has completed the switching, thereby completing the CHO switching process.

[0033] In a possible design of the third aspect, the method also includes: the target network device sends a third message to the AMF corresponding to another AMF information other than the target AMF information in the first AMF information and the second AMF information, and the third message is used to instruct the other AMF to release the connection established for the terminal device, thereby effectively improving resource utilization.

[0034] In a possible design of the third aspect, the third message includes a connection release reason value, which is a location abnormality or AMF unavailable.

[0035] In a possible design of the third aspect, the first CHO configuration information includes first CHO execution condition information, which is used to indicate the CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the first PLMN information includes the identifier of the first PLMN, the first AMF information includes the identifier of the first AMF, or includes the identifier of the first AMF and the identifier of the first PLMN; the second CHO configuration information includes second CHO execution condition information, which is used to indicate the CHO execution condition corresponding to the target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the second PLMN information includes the identifier of the second PLMN, the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

[0036] In a fourth aspect, an embodiment of the present application provides a communication device having the function of implementing the above-mentioned first aspect or any possible design of a terminal device in the first aspect. The device can be a terminal device or a chip included in the terminal device.

[0037] The communication device may also have the function of implementing the above-mentioned second aspect or any possible design of the source network device in the second aspect, or have the function of implementing the above-mentioned third aspect or any possible design of the target network device in the third aspect. The device can be a network device or a chip included in the network device.

[0038] The functions of the above-mentioned communication device can be implemented by hardware, or by hardware executing corresponding software. The hardware or software includes one or more modules, units or means corresponding to the above-mentioned functions.

[0039] In one possible design, the structure of the device includes a processing module and a transceiver module, wherein the processing module is configured to support the device in executing the corresponding functions of the terminal device in the first aspect or any design of the first aspect, or executing the corresponding functions of the source network device in the second aspect or any design of the second aspect, or executing the corresponding functions of the target network device in the third aspect or any possible design of the third aspect. The transceiver module is configured to support communication between the device and other communication devices. For example, when the device is a terminal device, it can receive first PLMN information and / or first AMF information of a candidate target cell, as well as first CHO configuration information and first area information corresponding to the first PLMN information and / or first AMF information, from the source network device. The communication device may also include a storage module, coupled to the processing module, which stores program instructions and data necessary for the device. As an example, the processing module may be a processor, the communication module may be a transceiver, and the storage module may be a memory. The memory may be integrated with the processor or provided separately from the processor.

[0040] In another possible design, the structure of the device includes a processor and may also include a memory. The processor is coupled to the memory and can be used to execute computer program instructions stored in the memory, so that the device performs the method in the above-mentioned first aspect or any possible design of the first aspect, or performs the method in the above-mentioned second aspect or any possible design of the second aspect, or performs the method in the above-mentioned third aspect or any possible design of the third aspect. Optionally, the device also includes a communication interface, and the processor is coupled to the communication interface. When the device is a network device or a terminal device, the communication interface can be a transceiver or an input / output interface; when the device is a chip included in the network device or a chip included in the terminal device, the communication interface can be the input / output interface of the chip. Optionally, the transceiver can be a transceiver circuit, and the input / output interface can be an input / output circuit.

[0041] In a fifth aspect, an embodiment of the present application provides a chip system, comprising: a processor, the processor being coupled to a memory, the memory being used to store programs or instructions, and when the program or instructions are executed by the processor, the chip system implements the above-mentioned first aspect or any possible method in the design of the first aspect, or implements the above-mentioned second aspect or any possible method in the design of the second aspect, or implements the above-mentioned third aspect or any possible method in the design of the third aspect.

[0042] Optionally, the chip system further includes an interface circuit, which is used to exchange code instructions with the processor.

[0043] Optionally, there may be one or more processors in the chip system, and the processor may be implemented in hardware or software. When implemented in hardware, the processor may be a logic circuit, an integrated circuit, etc. When implemented in software, the processor may be a general-purpose processor implemented by reading software code stored in a memory.

[0044] Optionally, the chip system may include one or more memories. The memory may be integrated with the processor or provided separately from the processor. For example, the memory may be a non-transient processor, such as a read-only memory (ROM), which may be integrated with the processor on the same chip or provided on separate chips.

[0045] In a sixth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program or instruction stored thereon. When the computer program or instruction is executed, the computer executes the method of the first aspect or any possible design of the first aspect, or executes the method of the second aspect or any possible design of the second aspect, or executes the method of the third aspect or any possible design of the third aspect.

[0046] In the seventh aspect, an embodiment of the present application provides a computer program product. When a computer reads and executes the computer program product, the computer executes the method of the first aspect or any possible design of the first aspect, or executes the method of the second aspect or any possible design of the second aspect, or executes the method of the third aspect or any possible design of the third aspect.

[0047] In an eighth aspect, an embodiment of the present application provides a communications system, comprising a source network device and a target network device. Optionally, the communications system may further include at least one terminal device. In a CHO handover scenario, before the terminal device determines to switch to the target network device, the target network device may be a candidate target network device configured by the source network device. Optionally, the communications system may further include one or more other candidate target network devices configured by the source network device. Optionally, the communications system may further include a core network device. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1a and Figure 1b A schematic diagram of a network architecture of a satellite communication system applicable to embodiments of the present application;

[0049] Figure 2 Schematic diagram of a geostationary cell formed for a mobile satellite;

[0050] Figure 3 Schematic diagram of a terrestrial mobile cell formed for a mobile satellite;

[0051] Figure 4 Schematic diagram of the switching process under the CHO mechanism;

[0052] Figure 5 A schematic diagram of a communication method provided in an embodiment of the present application;

[0053] Figure 6 This is a schematic diagram of different PLMNs corresponding to different areas covered by candidate target cells in an embodiment of the present application;

[0054] Figure 7 This is an example diagram of a source base station and a candidate target base station performing CHO preparation via a directly connected communication interface in an embodiment of the present application;

[0055] Figure 8 This is an example diagram of a source base station and a candidate target base station performing CHO preparation through forwarding by a core network device in an embodiment of the present application;

[0056] Figure 9 A specific example of a communication method provided in an embodiment of the present application;

[0057] Figure 10 A schematic structural diagram of a communication device provided in an embodiment of the present application;

[0058] Figure 11 Another structural diagram of a communication device provided in an embodiment of the present application;

[0059] Figure 12 A schematic structural diagram of another communication device provided in an embodiment of the present application;

[0060] Figure 13 Another structural diagram of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0062] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as: code division multiple access (CDMA) system, wideband code division multiple access (WCDMA) system, general packet radio service (GPRS), LTE system, LTE frequency division duplex (FDD) system, LTE time division duplex (TDD), universal mobile telecommunication system (UMTS), fifth generation (5G) system or NR system, or applied to future communication systems or other similar communication systems.

[0063] The technical solutions provided in the embodiments of the present application can be applied to non-terrestrial network (NTN) communication systems, as well as to scenarios where NTN and terrestrial networks (TN) are deployed in a hybrid manner. The NTN communication system may include a satellite communication system, a high altitude platform station (HAPS) communication system, or other non-terrestrial communication systems.

[0064] The following uses the NTN communication system as a satellite communication system as an example to explain in detail the network architecture of the present application.

[0065] Please refer to Figure 1a , is a schematic diagram of a network architecture of a satellite communication system applicable to an embodiment of the present application, wherein the network architecture includes a core network device 110, a wireless access network device 120, a satellite 130 and at least one terminal device (such as Figure 1a As an example, Figure 1a The core network equipment, wireless access network equipment and terminal equipment are located on the ground, while the satellites are located in the sky.

[0066] Among them, the radio access network device can communicate with the core network device in a wireless or wired manner. The core network device and the radio access network device can be independent and different physical devices, or the functions of the core network device and the logical functions of the radio access network device can be integrated into the same physical device, or the functions of part of the core network device and part of the radio access network device can be integrated into one physical device. It should be understood that the radio access network device mentioned in the embodiments of the present application may correspond to different devices in different communication systems, for example, in a 5G system, it corresponds to an access network device in 5G, such as gNB or ng-eNB, and in a 4G system, it corresponds to an access network device in 4G, such as eNB or en-gNB.

[0067] Communication between wireless access network equipment and terminal devices is achieved through satellite signal forwarding. This means that the satellite receives signals from wireless access network devices and forwards them to the ground, forming a satellite cell. This in turn provides coverage for terminal devices on the ground. In this scenario, the satellite acts as a relay node or transponder, and this scenario is also referred to as transparent satellite forwarding.

[0068] In the transparent forwarding mode, the satellite cell can be fixed on the ground (which can be denoted as a "fixed cell") or can move on the ground as the satellite moves (which can be denoted as a "mobile cell"). In the "fixed cell" scenario, the satellite cell is fixed on the ground, which means that the coverage of the satellite cell on the ground is fixed. It can be fixed for a period of time or permanently fixed. For example, for high-orbit satellites, since the satellite remains stationary relative to the ground, the satellite cell it forms is generally fixed relative to the ground. For low-orbit satellites, since the satellite moves relative to the ground, the satellite can adjust the launch angle of its antenna or other physical parameters to make the satellite cell formed relative to the ground fixed.

[0069] In a "mobile cell" scenario, the satellite cell moves with the satellite. That is, when the satellite moves, the satellite cell also moves on the ground with the satellite. Mobile cells typically occur because the satellite doesn't dynamically adjust its beam direction as it moves, causing the projection of the satellite's beam on the ground to move with it.

[0070] It should be noted that the embodiments of the present application do not specifically limit the existence scenario of mobile cells. When the satellite uses transparent forwarding to provide service coverage, a possible existence scenario of mobile cells can be: the satellite establishes a connection with the original wireless access network device. As the satellite moves, the cell under the original wireless access network device forwarded by the satellite moves with the satellite for a period of time, that is, the satellite maintains a connection with the original wireless access network device for a period of time; at a certain moment, the connection between the satellite and the original wireless access network device is disconnected due to reasons such as long distance and weak signal, and the satellite connects to a new wireless access network device. Thereafter, the satellite begins to forward the signal of the new wireless access network device, forming a new satellite cell. It can be understood that although the satellite is constantly running, the position of the wireless access network device on the ground does not change. Therefore, for the scenario where mobile cells exist, if the satellite forwards the signal of a wireless access network device on the ground, the satellite cell under the wireless access network device formed will also move within a certain range as the satellite moves, but the movement range of the satellite cell is usually around the wireless access network device.

[0071] Please refer to Figure 1b , is another network architecture diagram of a satellite communication system applicable to an embodiment of the present application, wherein the network architecture includes a core network device 110, a satellite 130 and at least one terminal device (such as Figure 1b As an example, Figure 1b The core network equipment and terminal equipment are located on the ground, while the satellites are located in the sky.

[0072] and Figure 1a The difference between the network architecture shown in is that Figure 1b In the network architecture shown, satellites can be equipped with wireless access network equipment, such as base stations. The satellites can generate their own cell signals and forward them to the ground to form satellite cells, providing service coverage for devices on the ground. Therefore, this scenario can also be called a regenerative satellite operation.

[0073] In the regenerative mode, the satellite cell moves with the satellite. That is, when the satellite moves, the cell it generates also moves on the ground, hence the term "mobile cell." Because this "mobile cell" is generated by the satellite itself, it can move on the ground following the satellite's orbit. Generally, when a satellite moves, a new satellite moves in to ensure the greatest possible continuous coverage. The coverage area of ​​the new satellite can be the same as or different from the previous satellite's. It is understood that due to differences in satellite orbit, beam transmission direction, and beam transmission capabilities, the ground coverage areas of two satellites may not be exactly the same.

[0074] although Figure 1a and Figure 1b Although only one terminal device is shown, it should be understood that a single radio access network device, satellite, or core network device can provide services for one or more terminal devices. The present embodiment of the present application does not limit the number of core network devices, radio access network devices, satellites, and terminal devices included in the satellite communication system. Furthermore, the terminal device may be fixed or mobile, which is also not limited in the present application.

[0075] The wireless access network device and the terminal device, as well as the terminal devices and the terminal devices, can communicate through the licensed spectrum (licensed spectrum), can also communicate through the unlicensed spectrum (unlicensed spectrum), or can also communicate through the licensed spectrum and the unlicensed spectrum at the same time. The wireless access network device and the terminal device, as well as the terminal devices and the terminal devices, can communicate through the spectrum below 6 gigahertz (GHz), can also communicate through the spectrum above 6 GHz, and can also communicate using the spectrum below 6 GHz and the spectrum above 6 GHz at the same time. The embodiments of the present application do not limit the spectrum resources used between the wireless access network device and the terminal device.

[0076] like Figure 2 The figure shows a schematic diagram of a geostationary cell formed by a mobile satellite. This diagram illustrates an ideal scenario: the terrestrial cell is completely stationary. When one satellite moves, another satellite completely covers the previous cell area. Geostationary cell mapping means that the cell's location remains stationary on the ground, and the mobile satellite can form these cells by adjusting its beam. It should be understood that when the satellite cell is a geostationary cell, the mobile satellite can provide service coverage through transparent forwarding.

[0077] For example, at time T1, cells 1 and 2 are covered by the beam of satellite 1, while cells 3 and 4 are covered by the beam of satellite 2. At time T2, although satellites 1 and 2 have both moved to the left, they can still adjust their beams to ensure coverage of cells 1, 2, 3, and 4. At time T3, compared to time T1, satellites 1 and 2 have moved far enough that satellite 1 can no longer provide coverage for cell 2 by adjusting its beam, and satellite 2 can no longer provide coverage for cell 4 by adjusting its beam. At this point, satellite 2 can provide coverage for cell 2, and satellite 3 can provide coverage for cell 4.

[0078] like Figure 3Figure 2 shows a schematic diagram of a terrestrial mobile cell formed by a mobile satellite. In this example, the terrestrial mobile cell mapping method means that the mobile satellite does not dynamically adjust its beam direction; the beam generated by the base station moves on the ground as the satellite / base station moves. It should be understood that when the satellite cell is a terrestrial mobile cell, the mobile satellite can provide service coverage through transparent forwarding or regeneration.

[0079] For example, at time T1, an area is covered by Cell 1 and Cell 2 formed by satellite 1, and Cell 3 and Cell 4 formed by satellite 2. Since Cell 1, Cell 2, Cell 3, and Cell 4 move along with the movement of satellite 1 and satellite 2, at time T3, the area is now covered by Cell 2 formed by satellite 1, Cell 3 and Cell 4 formed by satellite 2, and Cell 5 formed by the newly moved satellite 3.

[0080] The network architecture and business scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. Ordinary technicians in this field can know that with the evolution of communication network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0081] Some of the terms used in the embodiments of the present application are explained below to facilitate understanding by those skilled in the art.

[0082] 1) The terminal device involved in the embodiments of the present application is a device with wireless transceiver function, which can be deployed on land, including indoors or outdoors, handheld, wearable or vehicle-mounted; it can also be deployed on the water surface (such as ships, etc.); it can also be deployed in the air (for example, on airplanes, balloons and satellites, etc.). The terminal device can communicate with the core network via the radio access network (RAN) and exchange voice and / or data with the RAN. The terminal device can be a mobile phone, a tablet computer (Pad), a computer with wireless transceiver function, a mobile internet device (MID), a wearable device, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city, a wireless terminal in smart home, etc. The embodiments of this application do not limit the application scenarios. Terminal devices may also be referred to as user equipment (UE), mobile stations, and remote stations. The embodiments of this application do not limit the specific technology, device form, or name used by the terminal devices.

[0083] As an example and not a limitation, in the embodiments of the present application, the terminal device may also be a wearable device. Wearable devices may also be referred to as wearable smart devices or smart wearable devices, etc., which are a general term for wearable devices that are intelligently designed and developed using wearable technology for daily wear, such as glasses, gloves, watches, clothing, and shoes. A wearable device is a portable device that is worn directly on the body or integrated into the user's clothes or accessories. Wearable devices are not only hardware devices, but also achieve powerful functions through software support, data interaction, and cloud interaction. Broadly speaking, wearable smart devices include those that are fully functional, large in size, and can achieve complete or partial functions without relying on smartphones, such as smart watches or smart glasses, etc., as well as those that only focus on a certain type of application function and need to be used in conjunction with other devices such as smartphones, such as various smart bracelets, smart helmets, and smart jewelry for vital sign monitoring.

[0084] The terminal device in the embodiment of the present application can also be a vehicle-mounted module, vehicle-mounted module, vehicle-mounted component, vehicle-mounted chip or vehicle-mounted unit that is built into the vehicle as one or more components or units. The vehicle can implement the method of the present application through the built-in vehicle-mounted module, vehicle-mounted module, vehicle-mounted component, vehicle-mounted chip or vehicle-mounted unit.

[0085] 2) The radio access network device involved in the embodiments of this application is a device in the network used to connect terminal devices to the wireless network. The radio access network device can be a node in the radio access network, also known as a base station or a RAN node. In this application, a radio access network device refers to a radio access network device deployed on the ground or on a satellite. In the following description, a radio access network device may be simply referred to as an access network device or a network device.

[0086] The access network device may include an evolved base station (NodeB or eNB or e-NodeB, evolutionary Node B) in an LTE system or an evolved LTE system (LTE-Advanced, LTE-A), such as a traditional macro base station eNB and a micro base station eNB in ​​a heterogeneous network scenario, or may also include a next generation node B (gNB) in a 5G system or an NR system, or may also include a radio network controller (RNC), a node B (Node B, NB), a base station controller (BSC), a base transceiver station (BTS), a transmission reception point (TRP), a home base station (for example, a home evolved NodeB, or a home Node B, HNB), a base band unit (BBU), a baseband pool BBU pool, or a wireless fidelity (WiFi) access point (AP), an integrated access and backhaul (IAB) node, etc., or may also include a cloud radio access network (CRN). The embodiments of the present application are not limited to the centralized unit (CU) and / or distributed unit (DU) in the CloudRAN system.

[0087] For example, in one network architecture, a network device can be a CU node, a DU node, or an access network device that includes both a CU node and a DU node. Furthermore, a CU node can be divided into a control plane (CU-CP) and a user plane (CU-UP). The CU-CP is responsible for control plane functions, primarily including radio resource control (RRC) and packet data convergence protocol (PDCP)-C. PDCP-C is primarily responsible for encryption, decryption, integrity protection, and data transmission of control plane data. The CU-UP is responsible for user plane functions, primarily including SDAP and PDCP-U. SDAP is primarily responsible for processing core network data and mapping flows to bearers. PDCP-U is primarily responsible for encryption, decryption, integrity protection, header compression, sequence number maintenance, and data transmission of the data plane. The CU-CP and CU-UP can be connected via the E1 interface. The CU-CP represents the CU and connects to the core network via the Ng interface, connecting to the DU via F1-C (control plane). The CU-UP connects to the DU via F1-U (user plane). Of course, another possible implementation is that PDCP-C is also in CU-UP.

[0088] 3) The core network device involved in the embodiments of the present application refers to the device in the core network (CN) that provides service support for the terminal device. At present, some examples of core network devices include: AMF entity, session management function (SMF) entity, user plane function (UPF) entity, etc. Among them, the AMF entity is responsible for the access management and mobility management of the terminal device; the SMF entity is responsible for session management, such as user session establishment, etc.; the UPF entity is a functional entity of the user plane, mainly responsible for connecting to the external network. It should be noted that the entities in this application can also be referred to as network elements or functional entities, that is, the AMF entity can also be referred to as an AMF network element or an AMF functional entity, and the SMF entity can also be referred to as an SMF network element or an SMF functional entity. In the description below in this application, the core network device may refer to AMF.

[0089] 4) The satellite involved in the embodiments of the present application refers to a network device located on a satellite. For the sake of convenience, the "network device on the satellite" may be referred to as a "satellite". The satellite may be a low earth orbiting satellite (LEO) or a medium orbit satellite or other network device located in the sky and moving. Generally speaking, according to the orbital altitude of the satellite, the satellites in the satellite communication system can be divided into three categories: high orbit satellites (GEO), low orbit satellites (LEO) and medium orbit satellites. Among them, high orbit satellites can also be called geostationary satellites. The running speed of high orbit satellites is the same as the rotation speed of the earth. Therefore, high orbit satellites remain stationary relative to the ground. Correspondingly, the satellite cells formed by high orbit satellites are also stationary. Low orbit satellites can also be called near-Earth orbit satellites. Low orbit satellites move faster relative to the ground. Therefore, the satellite cells formed by low orbit satellites can move with the movement of the satellite. Medium orbit satellites refer to satellites whose orbital altitudes are between high orbit satellites and low orbit satellites.

[0090] 5) It should be noted that the terms "system" and "network" in the embodiments of the present application can be used interchangeably. "Multiple" means two or more. In view of this, in the embodiments of the present application, "multiple" can also be understood as "at least two". "At least one" can be understood as one or more, for example, one, two or more. For example, including at least one means including one, two or more, and there is no limit on which ones are included. For example, including at least one of A, B and C, then the included ones may be A, B, C, A and B, A and C, B and C, or A and B and C. Similarly, the understanding of descriptions such as "at least one" is similar. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / ", unless otherwise specified, generally indicates that the previous and subsequent associated objects are in an "or" relationship.

[0091] Unless otherwise specified, the ordinal numbers such as "first" and "second" mentioned in the embodiments of the present application are used to distinguish multiple objects, and are not used to limit the order, timing, priority or importance of multiple objects, and the descriptions of "first" and "second" do not limit the objects to be different.

[0092] The cell involved in the embodiments of the present application may be an NTN cell. The cell in the present application will be described in detail below by taking the NTN cell as a satellite cell as an example.

[0093] In addition to the above-mentioned features related to mobility, another important feature of satellite cells is their large coverage. The coverage diameter of a satellite cell can reach tens to thousands of kilometers. Therefore, there is a situation where a satellite cell covers the geographical areas of multiple countries or covers the service areas of multiple operators. Generally speaking, a satellite can indicate that it can support services in multiple countries / operators by broadcasting information about multiple PLMNs (such as PLMN identification information, etc.) and / or information about AMFs (such as AMF identification information, etc.). The terminal device can determine the appropriate PLMN and / or AMF to access based on the mapping relationship between its own location, the area covered by the cell, and the PLMN and / or AMF.

[0094] For example, cell C covers the geographic areas of countries A and B. Country A corresponds to PLMN1 and / or AMF1, and country B corresponds to PLMN2 and / or AMF2. Cell C can broadcast information about PLMN1 and / or AMF1, as well as information about PLMN2 and / or AMF2. It can be understood that "country A corresponds to PLMN1 and / or AMF1" means that the PLMN deployed in country A that manages cell C is PLMN1, and / or the AMF to which the access network equipment to cell C is connected is AMF1; and "country B corresponds to PLMN2 and / or AMF2" means that the PLMN deployed in country B that manages cell C is PLMN2, and / or the AMF to which the access network equipment to cell C is connected is AMF2.

[0095] In this way, for UE1 in country A and within the coverage of cell C, UE1 can access cell C through PLMN1 and / or AMF1; or, when UE1 wants to access cell C, it can access cell C through PLMN1 and / or AMF1; or, when UE1 wants to access cell C, UE1 can access the cell corresponding to PLMN1 and / or AMF1; or, when UE1 wants to access cell C, the core network device to which the access network device that UE1 can access is connected is AMF1, and the access network device that UE1 can access belongs to PLMN1.

[0096] Similarly, for UE2 in country B and within the coverage of cell C, UE2 can access cell C through PLMN2 and / or AMF2; or, when UE2 wants to access cell C, it can access cell C through PLMN2 and / or AMF2; or, when UE2 wants to access cell C, UE2 can access the cell corresponding to PLMN2 and / or AMF2; or, when UE2 wants to access cell C, the core network device to which the access network device that UE2 can access is connected is AMF2, and the access network device that UE2 can access belongs to PLMN2.

[0097] Considering the different communication strategies of different countries or operators, satellite cells can be divided into finer granularity. For example, the entire service coverage area of ​​a satellite cell can be divided into multiple regular or irregular areas, which can be called virtual cells or virtual areas. This can better match the geographical regions of different countries or the service areas of different operators. Different areas within the same satellite cell can correspond to different PLMNs and / or AMFs, thus forming multiple virtual cells within the same satellite cell, thereby effectively managing the mobility of terminal devices based on different areas.

[0098] The embodiments of the present application can also be applied to the scenario of cell switching, where the terminal device may switch from the source network device to the target network device due to movement of location, change of service, change of network coverage or other reasons. Wherein, the source network device refers to the network device that the terminal device accesses before performing the switching, or the network device that provides services to the terminal device before the switching; the target network device refers to the network device to which the terminal device needs to switch, or the network device that the terminal device accesses after successfully performing the switching, or the network device that provides services to the terminal device after the switching is successful. Correspondingly, the source cell refers to the cell that the terminal device accesses before performing the switching, and the source cell is the cell covered by the source network device, or the source cell is the cell under the jurisdiction of the source network device, or the source cell belongs to the source network device. The target cell refers to the cell that the terminal device accesses after performing the switching, and the target cell is the cell covered by the target network device, or the target cell is the cell under the jurisdiction of the target network device, or the target cell belongs to the target network device.

[0099] In order to effectively improve the switching reliability, the above-mentioned cell switching can be CHO. In the CHO mechanism, the network (such as the source network device) can configure one or more candidate target cells for the terminal device, and the candidate target cells can also be referred to as candidate cells. If the network configures multiple candidate target cells for the terminal device, the network can send the CHO configuration information corresponding to the multiple candidate target cells to the terminal device through one or more RRC messages. The above-mentioned RRC message can be a newly defined message (such as CondRRCReconfiguration, or with other naming / expression forms, not limited) or reuse of an existing RRC message (such as an RRC reconfiguration message).

[0100] The source network device may send an RRC message to the terminal device when the source link signal quality is good. The RRC message may include CHO configuration information corresponding to at least one candidate target cell. The CHO configuration information corresponding to a candidate target cell may include CHO execution condition information and relevant information of the candidate target cell.

[0101] Among them, the relevant information of the candidate target cell may include one or more of the following information: the cell radio network temporary identifier (C-RNTI) allocated by the candidate target cell to the terminal device, the random access channel (RACH) resource information required to access the candidate target cell, the index information corresponding to the candidate target cell (such as the measurement identifier measID corresponding to the cell and / or the CHO reconfiguration identifier CondReconfigId corresponding to the cell), the cell global identifier (CGI) of the candidate target cell, the physical cell identifier (PCI) of the candidate target cell, the frequency information corresponding to the candidate target cell, the physical layer configuration parameters corresponding to the candidate target cell, the media access control (MAC) layer configuration parameters, the radio link control (RLC) layer configuration parameters, the packet data convergence (PDCP) layer configuration parameters, the service data adaptation protocol (SDAP) layer configuration parameters, the RRC layer configuration parameters, etc. The frequency information of the candidate target cell may include one or more of the following: the absolute frequency of the synchronization signal block (SSB) (such as absoluteFrequencySSB), the absolute frequency position of the reference resource module (common RB0) (such as absoluteFrequencyPointA), the frequency bandwidth list (such as frequencyBandList), and the subcarrier spacing (SCS) specific carrier list (such as scs-SpecificCarrierList).

[0102] The CHO execution condition information is used to indicate the CHO execution condition corresponding to the candidate target cell. The CHO execution condition may also be referred to as a CHO trigger condition. Taking a CHO execution condition based on cell signal quality as an example (i.e., the trigger quantity in the CHO execution condition is the cell signal quality), the CHO execution condition information may include a CHO execution event type and a corresponding threshold value. The CHO execution event type may include event A3, event A4, event A5, event B1, event B2, or other execution event types.

[0103] A candidate target cell may be configured with one or more CHO execution conditions. For example, a candidate target cell may be configured with one execution event type, but may be configured with at most two different trigger quantities, and at least two different threshold values ​​for each trigger quantity, where the trigger quantity is the signal quality of the cell, for example, may include one or more of reference signal received power (RSRP), reference signal received quality (RSRQ), and signal to interference plus noise ratio (SINR). Alternatively, a candidate target cell may be configured with at least two different execution event types and threshold values ​​corresponding to each execution event type. The CHO execution event types and / or threshold values ​​corresponding to the execution event types corresponding to different candidate target cells may be the same or different, without limitation.

[0104] It is understood that the source cell, target cell, or candidate target cell in the embodiments of the present application may be the NTN cell described above, such as a satellite cell. That is, the service coverage area of ​​the source cell, target cell, or candidate target cell may be divided into multiple areas, and different areas may correspond to different PLMNs and / or different AMFs, forming different virtual cells.

[0105] Figure 4The handover process under the CHO mechanism is exemplified. In this example, the source base station configures two candidate target cells for the UE, and the two candidate target cells are respectively managed by candidate target base station 1 and candidate target base station 2. The handover process may include: in step S401, the source base station sends a measurement configuration to the UE, and correspondingly receives a measurement report reported by the UE in step S402. In steps S403-a and S404-a, the source base station performs CHO handover preparation with the candidate target base station 1. The source base station may send a handover request message to the candidate target base station 1 and receive a handover request confirmation message from the candidate target base station 1. The handover request confirmation message may include the CHO configuration information of the candidate target cell 1. In steps S403-b and S404-b, the source base station performs CHO handover preparation with the candidate target base station 2. The source base station may send a handover request message to the candidate target base station 2 and receive a handover request confirmation message from the candidate target base station 2. The handover request confirmation message may include the CHO configuration information of the candidate target cell 2. In step S405, the source base station may send an RRC message to the UE, and the RRC message includes the CHO configuration information corresponding to the candidate target cell 1 and the candidate target cell 2 respectively. Furthermore, in step S406, after the UE receives the RRC message, it may determine whether the CHO execution conditions of the candidate target cell 1 and the candidate target cell 2 are met according to the respective CHO configuration information of the candidate target cell 1 and the candidate target cell 2, and use the cell that meets the CHO execution conditions among the candidate target cell 1 and the candidate target cell 2 as the target cell. Subsequently, the UE may initiate random access to the base station to which the target cell belongs in order to access the target cell. Assuming that the UE determines that the candidate target cell 1 is the target cell, in step S407, the UE may perform a random access process with the candidate target base station 1 (i.e., the target base station). After the random access process is successful, in step S408, the UE may send an RRC reconfiguration completion message to the candidate target base station 1 (i.e., the target base station). It can be understood that after the UE determines that the candidate target cell 1 is the target cell, the candidate target base station may also be referred to as the target base station. It should be noted that, Figure 4 This is only an example of the CHO process. The CHO process may have other variations, which are not limited in this application. Figure 4 Each step in the process may be optional and the execution order of each step may be changed.

[0106] Specifically, the UE can determine whether the CHO execution condition is met based on the CHO configuration information. In an example, assuming that the CHO execution event type configured for the candidate target cell 1 is an A3 event, the trigger quantity is the signal quality of the cell, and the corresponding threshold value is the first threshold, then when the cell signal quality of the candidate target cell 1 is higher than the first threshold of the cell signal quality of the serving cell, it can be considered that the candidate target cell 1 meets the CHO execution condition, and the candidate target cell 1 can be determined as the target cell. It should be noted that the signal quality may include one or more of RSRP, RSRQ and SINR. For example, the signal quality may include RSRP and RSRQ, or include RSRP and SINR, or include other parameters, and is not limited. When the signal quality includes multiple parameters, each of them can be considered as a separate trigger quantity. For example, when the signal quality includes RSRP and RSRQ, RSRP can be considered as a trigger quantity and RSRQ as another trigger quantity. For different trigger quantities, the corresponding first thresholds can be the same or different, and are not limited. Specifically, for candidate target cell 1, the A3 event is configured, and two trigger quantities are configured, namely RSRP and RSRQ. The first threshold corresponding to RSRP is configured as E, and the first threshold corresponding to RSRQ is configured as F. Then, when the RSRP of candidate target cell 1 is higher than the RSRP of the serving cell by E, and the RSRQ of candidate target cell 1 is higher than the RSRQ of the serving cell by F, it can be considered that candidate target cell 1 meets the CHO execution conditions, and the candidate target cell 1 can be determined as the target cell.

[0107] In another example, assuming that the CHO execution event type configured for candidate target cell 1 is an A5 event, the trigger quantity is the signal quality of the cell, and the corresponding threshold values ​​configured are the second threshold and the third threshold, then when the cell signal quality of candidate target cell 1 is higher than the second threshold and the cell signal quality of the serving cell is lower than the third threshold, it can be considered that candidate target cell 1 meets the CHO execution conditions, and the candidate target cell 1 can be determined as the target cell.

[0108] In another example, assuming that the CHO execution event type configured for the candidate target cell 1 is an A3 event or an A5 event, the trigger quantity configured for the A3 event is RSRP, and the corresponding threshold value configured for the A3 event is the first threshold; the trigger quantity configured for the A5 event is RSRQ, and the corresponding threshold value configured for the A5 event is the second threshold and the third threshold, then when the RSRP of the candidate target cell 1 is higher than the RSRP of the serving cell by the first threshold, and when the RSRQ of the candidate target cell 1 is higher than the second threshold, and the RSRQ of the serving cell is lower than the third threshold, it can be considered that the candidate target cell 1 meets the CHO execution conditions, and the candidate target cell 1 can be determined as the target cell.

[0109] It should be noted that the above examples are merely illustrative and the embodiments of the present application are not limited thereto.

[0110] Considering the significant propagation delay in NTN communications, which can cause handover failures, the CHO mechanism in NTN communication systems offers significant benefits. In NTN communication systems, since satellites have regular motion patterns, network equipment can access ephemeris data. For example, they can determine which cell / base station serves a terminal device at a specific geographic location, or which cell / base station served a terminal device during a specific time period. Therefore, the CHO mechanism in NTN communication systems can incorporate criteria based on time and location information to determine whether CHO execution conditions are met.

[0111] Specifically, the CHO mechanism of the NTN communication system may include the following three types of CHO execution condition information:

[0112] 1) Based on signal quality. The CHO execution condition information may include the CHO execution event type and the corresponding threshold value. For details, please refer to the above description of the CHO execution condition information.

[0113] 2) Based on location. The CHO execution condition information may be geographic location information. For example, in one embodiment, the geographic location information may be the geographic location information of the terminal device on the ground. For example, the CHO execution condition information may include longitude and latitude values. The longitude and latitude values ​​may be used to determine a certain area or a fixed point. When the geographic location of the terminal device meets the longitude and latitude requirements, such as when the terminal device moves into the area or fixed point indicated by the longitude and latitude values, the terminal device may perform handover. Alternatively, in another embodiment, the geographic location information may be the distance between the terminal device and the satellite. For example, the CHO execution condition information may include a distance threshold. When the distance between the terminal device and the satellite reaches the threshold, the UE may perform handover. Alternatively, in yet another embodiment, the geographic location information may be global positioning system (GPS) information or timing advance (TA) or other information. In this embodiment, a candidate target cell may correspond to one or more CHO execution condition information, and the candidate cell has corresponding relevant information (i.e., relevant information of the candidate target cell). The CHO execution condition information corresponding to different candidate target cells may be the same or different, without limitation.

[0114] 3) Based on time / timer. The CHO execution condition information may be time information. Exemplarily, in one embodiment, the CHO execution condition information may be an absolute time value, such as a specific moment value (such as coordinated universal time (UTC) 12:00) or a specific time period value (such as UTC 12:00-UTC13:00), that is, when the absolute time arrives, the terminal device may perform switching. Alternatively, in another embodiment, the CHO execution condition information may be a relative time value, such as the effective duration of a timer, that is, after the terminal device receives the RRC message containing the CHO configuration information, it starts the timer, and when the effective duration of the timer arrives, the terminal device may perform switching. In this embodiment, a candidate cell may correspond to one or more CHO execution condition information, and the candidate target cell has corresponding relevant information (i.e., relevant information of the candidate target cell), and the CHO execution condition information corresponding to different candidate target cells may be the same or different.

[0115] When configuring CHO, the network may configure at least one of the three types of CHO execution condition information as CHO execution condition information. For example, the CHO execution event type and corresponding threshold and absolute time values ​​may be configured as CHO execution condition information. When the absolute time arrives and the signal quality of the corresponding candidate target cell meets the conditions, the terminal device may determine the candidate target cell as the target cell and perform handover.

[0116] It is understood that in the embodiments of the present application, the terminal device and / or the network device may perform some or all of the steps in the embodiments of the present application. These steps or operations are merely examples, and the embodiments of the present application may also perform other operations or variations of various operations. In addition, the various steps may be performed in a different order than those presented in the embodiments of the present application, and it is possible that not all of the operations in the embodiments of the present application need to be performed.

[0117] The embodiments of the present application use the PLMN and AMF entities as examples to illustrate the methods involved, but the embodiments of the present application are not limited to the PLMN and AMF entities. The PLMN can also be other communication networks, and the AMF entity can also be other entities or devices that can implement mobility management functions, or entities or devices that implement similar functions in a communication network.

[0118] Please refer to Figure 5 , is a flow chart of a communication method provided in an embodiment of the present application, the method comprising:

[0119] Step S501: The candidate target network device sends first information of the candidate target cell to the source network device, where the first information includes first PLMN information and / or first AMF information, and second PLMN information and / or second AMF information; wherein the first information also includes first CHO configuration information and first area information corresponding to the first PLMN information and / or first AMF information, and second CHO configuration information and second area information corresponding to the second PLMN information and / or second AMF information, where the first area information is used to indicate the first area covered by the candidate target cell, and the second area information is used to indicate the second area covered by the candidate target cell.

[0120] Correspondingly, the source network device may receive the first information of the candidate target cell from the candidate target network device.

[0121] Specifically, the content of the first information may include the following situations:

[0122] 1) The first information includes the first PLMN information and the second PLMN information, as well as the first CHO configuration information and the first area information corresponding to the first PLMN information, and the second CHO configuration information and the second area information corresponding to the second PLMN information.

[0123] 2) The first information includes the first AMF information and the second AMF information, as well as the first CHO configuration information and the first area information corresponding to the first AMF information, and the second CHO configuration information and the second area information corresponding to the second AMF information.

[0124] 3) The first information includes the first PLMN information and the first AMF information, the second PLMN information and the second AMF information, as well as the first CHO configuration information and the first area information corresponding to the first PLMN information and the first AMF information, and the second CHO configuration information and the second area information corresponding to the second PLMN information and the second AMF information.

[0125] 4) The first information includes the first PLMN information and the second AMF information, as well as the first CHO configuration information and the first area information corresponding to the first PLMN information, and the second CHO configuration information and the second area information corresponding to the second AMF information.

[0126] 5) The first information includes the first AMF information and the second PLMN information, as well as the first CHO configuration information and the first area information corresponding to the first AMF information, and the second CHO configuration information and the second area information corresponding to the second PLMN information.

[0127] In order to clearly describe the various possible forms of expression of the content contained in the first information as described above, the method provided in this application will be exemplified below by using the statement that the first information includes first PLMN information and / or first AMF information, and second PLMN information and / or second AMF information.

[0128] Step S502: The source network device sends the first information of the candidate target cell to the terminal device.

[0129] Correspondingly, the terminal device can receive the first information of the candidate target cell from the source network device.

[0130] In this embodiment of the present application, a candidate target cell is a cell that supports first PLMN information and / or first AMF information, as well as second PLMN information and / or second AMF information, and a candidate target network device is a network device that manages the candidate target cell. In the transparent forwarding mode, the network device refers to a terrestrial wireless access network device. In the regeneration mode, the network device refers to a wireless access network device deployed on a satellite or a satellite that has the functionality of a wireless access network device, or in other words, the wireless access network device is embedded in the satellite.

[0131] The first PLMN information is used to indicate the first PLMN, and the second PLMN information is used to indicate the second PLMN. In other words, the first PLMN information corresponds to the first PLMN, and the second PLMN information corresponds to the second PLMN. For example, the first PLMN information may include an identifier of the first PLMN, and the second PLMN information may include an identifier of the second PLMN. That is, the PLMN information described in the embodiments of the present application may be represented by a PLMN identifier (e.g., PLMN-identifier). Similarly, the first AMF information is used to indicate the first AMF, and the second AMF information is used to indicate the second AMF. In other words, the first AMF information corresponds to the first AMF, and the second AMF information corresponds to the second AMF. For example, the first AMF information may include an identifier of the first AMF, or include an identifier of the first AMF and an identifier of the first PLMN, and the second AMF information may include an identifier of the second AMF, or include an identifier of the second AMF and an identifier of the second PLMN. That is, the AMF information described in the embodiments of the present application may be identified by an AMF identifier (e.g., AMF-identifier), or represented by a combination of an AMF identifier (e.g., AMF-identifier) ​​and a PLMN identifier (e.g., PLMN-identifier).

[0132] Exemplarily, the candidate target cell may be a cell that supports geographical areas covering multiple countries or service areas of multiple operators. For example, the candidate target cell may cover the geographical areas of country A (or operator A) and country B (or operator B), wherein country A (or operator A) may correspond to the first PLMN or the first AMF, and country B (or operator B) may correspond to the second PLMN or the second AMF. In other words, the PLMN deployed by country A (or operator A) to manage the candidate target cell is the first PLMN, and the AMF is the first AMF; the PLMN deployed by country B (or operator B) to manage the candidate target cell is the second PLMN, and the AMF is the second AMF.

[0133] like Figure 6 As shown, assuming that the area covered by country A (or operator A) in the candidate target cell is recorded as the first area, and the area covered by country B (or operator B) in the candidate target cell is recorded as the second area, it can be considered that the candidate target cell covers the first area and the second area, wherein the first area corresponds to the first PLMN and / or the first AMF, and the second area corresponds to the second PLMN and / or the second AMF.

[0134] The first area information is used to indicate the geographical location / range of the first area, and the second area information is used to indicate the geographical location / range of the second area. The area information can be represented by one or more geographical location information of longitude information, latitude information and altitude information, or it can be represented by combining other parameters (such as diameter / radius information) on the basis of one or more information of longitude information, latitude information and altitude information, or it can be represented by an area identifier (such as an ID or index), wherein there is a mapping relationship between the area identifier and the specific geographical location / range of the area it represents (for example, the position / range represented by longitude information, latitude information and altitude information), and the mapping relationship can be a protocol agreement or a network device sent to the terminal device through a system message or an RRC message or a layer 2 message, which is not limited by this application. Of course, the area information can also be represented in other forms, such as the name or identifier of the administrative area, etc., which is not limited by this application.

[0135] Furthermore, the candidate target network device may configure CHO configuration information for different PLMNs and / or AMFs in the candidate target cell. Specifically, the first CHO configuration information may correspond to the first PLMN and / or the first AMF, and the second CHO configuration information may correspond to the second PLMN and / or the second AMF.

[0136] The first CHO configuration information may include first CHO execution condition information, which is used to indicate the CHO execution condition (which may be referred to as the first CHO execution condition) corresponding to the candidate target cell and the first PLMN and / or the first AMF. The first CHO execution condition may be one or more of a CHO execution condition based on signal quality, a CHO execution condition based on time / timer, or a CHO execution condition based on location. Accordingly, the first CHO execution condition information may include one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location. The specific implementation of the first CHO execution condition information can refer to the relevant introduction to the CHO execution condition information above, which will not be repeated here.

[0137] Similarly, the second CHO configuration information may include second CHO execution condition information, which is used to indicate the CHO execution condition (which may be referred to as the second CHO execution condition) of the candidate target cell corresponding to the second PLMN and / or the second AMF. The second CHO execution condition may be one or more of a signal quality-based CHO execution condition, a time / timer-based CHO execution condition, or a location-based CHO execution condition. Accordingly, the second CHO execution condition information may include one or more of signal quality-based execution condition information, time / timer-based execution condition information, or location-based execution condition information.

[0138] It is worth noting that in an embodiment of the present application, the content included in the first CHO configuration information and the content included in the second CHO configuration information may be completely identical, partially identical, or completely different. For example, the RACH resource information included in the first CHO configuration information and the RACH resource information included in the second CHO configuration information may be the same or different, and the RACH resource information may include a preamble (such as a preamble index), time-frequency resources, etc. Therefore, the difference between the two RACH resource information may refer to different preambles and / or different time-frequency resources. For another example, the first CHO execution condition information included in the first CHO configuration information and the second CHO execution condition information included in the second CHO configuration information may be the same or different. For another example, the key information / parameters included in the first CHO configuration information for the terminal device to access the candidate target cell and the key information / parameters included in the second CHO configuration information for the terminal device to access the candidate target cell may be the same or different. In an embodiment of the present application, the source network device and the candidate target network device can respectively perform the CHO preparation process for the first PLMN and / or the first AMF of the candidate target cell, and the second PLMN and / or the second AMF, and send the content related to the first PLMN information and / or the first AMF information of the candidate target cell, and the content related to the second PLMN information and / or the second AMF information to the terminal device.

[0139] The following describes in detail the CHO preparation process between the network device (such as the source network device, the candidate target network device) and the first PLMN and / or the first AMF.

[0140] In a possible implementation, if there is a directly connected communication interface (such as an Xn interface) between the source network device and the candidate target network device, the source network device can exchange information with the candidate target network device through the directly connected communication interface, perform CHO preparation, and obtain corresponding CHO configuration information. In this case, the switching process can be called a CHO process based on the Xn interface. For example, Figure 7As shown, in step S701, the source base station can directly send a handover request message to the candidate target base station. In step S702, after receiving the handover request message, the candidate target base station can perform admission control / handover preparation according to the handover request message. If the candidate target base station decides to accept the handover request, the candidate target base station can perform resource configuration, configuration of CHO configuration information and other processing. Furthermore, in step S703, the candidate target base station can send a handover request confirmation message to the source base station, and the handover request confirmation message includes the first PLMN information and / or the first AMF information, as well as the first CHO configuration information and the first area information corresponding to the first PLMN information and / or the first AMF information. The first area information is used to indicate the first area covered by the candidate target cell.

[0141] In another possible implementation, if there is no directly connected communication interface between the source network device and the candidate target network device, the source network device may indirectly exchange information with the candidate target network device through the communication interface between the wireless access network device and the core network device, that is, perform CHO preparation through the intermediate forwarding of the core network device. The core network device may be, for example, an AMF, and the communication interface between the wireless access network device and the core network device may be, for example, an NG interface. In this case, the handover process may be referred to as a CHO process based on the NG interface. For example, Figure 8As shown, when the source base station and the candidate target base station belong to different AMFs or are managed by different AMFs, in step S801, the source base station may send a first handover request message to the source AMF. The source AMF refers to the AMF that manages the source base station. The first handover request message may be a HOrequired message or have other names and is not limited. In step S802, after receiving the first handover request message, the source AMF may send a second handover request message to the target AMF1. The target AMF1 refers to the AMF that manages the candidate target base station. It may be the first AMF described above or the AMF corresponding to the first PLMN. The second handover request message may be a Namf_Communication_CreatUEContext Request message or have other names and is not limited. In step S803, after receiving the second handover request message, the target AMF1 may send a third handover request message to the candidate target base station. The third handover request message may be a HO request message or have other names and is not limited. In step S804, after receiving the third request message, the candidate target base station may perform admission control / handover preparation for the UE's handover based on the third request message. If the candidate target base station decides to accept the handover request, the candidate target base station may perform resource configuration, CHO configuration information, and other processes. Furthermore, in step S805, the candidate target base station may send a third handover response message to the target AMF1. This third handover response message may be a HO request ACK message or have other names, without limitation. In step S806, after receiving the third handover response message, the target AMF1 may send a second handover response message to the source AMF. This second handover response message may be a Namf_Communication_CreateUEContext Response message or have other names, without limitation. In step S807, after receiving the second handover response message, the source AMF may send a first handover response message to the source base station. This first handover response message may be a HO command message or have other names, without limitation. The third handover response message, the second handover response message, and the first handover response message may include first PLMN information and / or first AMF information, as well as first CHO configuration information and first area information corresponding to the first PLMN and / or first AMF. The first area information is used to indicate the first area covered by the candidate target cell. It should be noted that the source AMF and the target AMF1 can be the same or different, and there is no limitation.

[0142] Furthermore, after the source network device obtains the first PLMN information and / or first AMF information of the candidate target cell, and the first CHO configuration information and first area information corresponding to the first PLMN and / or first AMF from the candidate target network device, the source network device can send a first RRC message to the terminal device, which includes the first PLMN information and / or first AMF information of the candidate target cell, and the first CHO configuration information and first area information corresponding to the first PLMN and / or first AMF.

[0143] The CHO preparation process performed between the network device (such as the source network device, the candidate target network device) and the second PLMN and / or the second AMF can refer to the implementation method of the CHO preparation process performed between the network device (such as the source network device, the candidate target network device) and the first PLMN and / or the first AMF described above, and will not be elaborated here.

[0144] Similarly, after the source network device obtains the second PLMN information and / or second AMF information of the candidate target cell from the candidate target network device, and the second CHO configuration information and second area information corresponding to the second PLMN and / or second AMF, the source network device can send a second RRC message to the terminal device, which includes the second PLMN information and / or second AMF information of the candidate target cell, and the second CHO configuration information and second area information corresponding to the second PLMN and / or second AMF.

[0145] The second RRC message and the first RRC message mentioned above may be the same RRC message or different RRC messages, which is not limited in this application. That is, when the candidate target cell is an NTN cell that supports multiple PLMNs and / or multiple AMFs, the source network device may send CHO configuration information, area information, etc. corresponding to the multiple PLMNs and / or AMFs of the candidate target cell to the terminal device through one or more RRC messages.

[0146] According to the above-mentioned CHO switching preparation process, although the embodiment of the present application describes in step S501 and step S502 that the candidate target network device sends the first information of the candidate target cell to the source network device, and the source network device sends the first information of the candidate target cell to the terminal device, the embodiment of the present application is not limited to the situation where all the contents contained in the first information are carried as a whole in one RRC message. The different PLMN information and / or AMF information in the first information, and the corresponding CHO configuration information and area information can be sent respectively through different RRC messages, which is more in line with the concept of the candidate target network device independently managing and configuring the different PLMNs and / or AMFs it supports.

[0147] It should be noted that the source network device can configure one or more candidate target cells for the terminal device. The embodiment of the present application takes a candidate target cell configured by the source network device for the terminal device as an example to illustrate the specific CHO switching mechanism when the candidate target cell is an NTN cell that supports multiple PLMNs and / or multiple AMFs. The other candidate target cells configured by the source network device for the terminal device may also be NTN cells covering geographical areas of multiple countries or service areas of multiple operators (i.e., NTN cells that support multiple PLMNs and / or AMFs), or they may not be, and are not limited. Moreover, the other candidate target cells configured by the source network device for the terminal device may belong to the same network device as the candidate target cells illustrated in the embodiment of the present application, or they may belong to different network devices, and this application does not limit this.

[0148] Optionally, if the source network device configures multiple candidate target cells for the terminal device, the source network device may also obtain CHO configuration information for the other candidate target cells from the other candidate target network devices, and transmit the CHO configuration information of the other candidate target cells to the terminal device in a third RRC message. That is, the source network device may transmit a third RRC message to the terminal device, the third RRC message including the CHO configuration information corresponding to the other candidate target cells. It will be appreciated that, as previously described, the other candidate target cells may or may not also be candidate cells that support multiple PLMNs and / or AMFs, and this is not a limitation. Therefore, when the candidate target cell also supports multiple PLMNs and / or AMFs, the third RRC message may also include PLMN information and / or AMF information corresponding to the CHO configuration information of the other candidate target cells, as well as area information. Similarly, the third RRC message and the first RRC message may be the same RRC message or different RRC messages, and this is not a limitation. The third RRC message and the second RRC message may be the same RRC message or different RRC messages, and this is not a limitation.

[0149] Step S503: The terminal device determines the target cell and target PLMN information and / or target AMF information based on the first information and the area where it is currently located.

[0150] Specifically, if the first CHO execution condition in the first CHO configuration information is met and the terminal device is currently located in the first area, the terminal device can determine that the candidate target cell is the target cell, and determine the first PLMN information as the target PLMN information, and / or determine the first AMF information as the target AMF information.

[0151] Optionally, if the first CHO execution condition in the first CHO configuration information and the second CHO execution condition in the second CHO configuration information are both met, and the terminal device is currently located in the first area, the terminal device can determine that the candidate target cell is the target cell, and determine that the first PLMN information is the target PLMN information, and / or determine that the first AMF information is the target AMF information.

[0152] The target PLMN information is used to indicate the target PLMN, and the target AMF information is used to indicate the target AMF, or in other words, the target PLMN information corresponds to the target PLMN, and the target AMF information corresponds to the target AMF.

[0153] Optionally, the terminal device may also determine that the first area is the target area, and the target PLMN information and / or target AMF information is the PLMN information and / or AMF information corresponding to the target area.

[0154] In an embodiment of the present application, after the terminal device receives the first CHO configuration information and the second CHO configuration information of the candidate target cell, it can determine whether the first CHO execution condition in the first CHO configuration information and the second CHO execution condition in the second CHO configuration information are met, and determine the target cell, target PLMN and / or target AMF in combination with the terminal device's own location (such as the current area), the PLMN and / or AMF supported by the terminal device, etc.

[0155] It is worth noting that the first area can also be understood as an area that overlaps with the area where the terminal device is located in one or more areas that meet the CHO execution conditions in the candidate target cell. Furthermore, if the terminal device located in the first area can determine the cell that meets the CHO execution conditions as the target cell, the terminal device is required to be able to support the first PLMN and / or the first AMF corresponding to the first area. The terminal device can also support the second AMF and / or the second PLMN at the same time, without limitation. If the terminal device does not support the first AMF and / or the first PLMN, then even if the cell meets the corresponding CHO execution conditions, it cannot be determined as the target cell.

[0156] In view of this, a possible implementation method is that if the first CHO execution condition in the first CHO configuration information is met, and the terminal device is currently located in the first area, and the terminal device supports the first PLMN and / or first AMF corresponding to the first area, then the terminal device can determine the candidate target cell as the target cell, and determine the first PLMN as the target PLMN, and / or determine the first AMF as the target AMF.

[0157] Another possible implementation is that if the first CHO execution condition in the first CHO configuration information and the second CHO execution condition in the second CHO configuration information are both met, and the terminal device is currently located in the first area, and the terminal device supports the first PLMN and / or first AMF corresponding to the first area, then the terminal device can determine the candidate target cell as the target cell, and determine the first PLMN as the target PLMN, and / or determine the first AMF as the target AMF.

[0158] It should be understood that the first area is only an example. If the second CHO execution condition in the second CHO configuration information is met, and the terminal device is currently located in the second area, and the terminal device supports the second PLMN and / or second AMF corresponding to the second area, then the terminal device can determine the candidate target cell as the target cell, and determine the second PLMN as the target PLMN, and / or determine the second AMF as the target AMF. Optionally, the second area can be determined as the target area. In this case, the relevant processing of the second area can refer to the relevant description of the first area above and will not be repeated.

[0159] Exemplarily, the terminal device can determine, based on its current location, a candidate target cell under the jurisdiction of the PLMN and / or AMF that supports / allows the terminal device to access at its location (or the area to which the location belongs) as the target cell.

[0160] For example, combined with Figure 6 As shown, assuming that UE1 supports PLMN1 and PLMN2, if UE1 determines that cell1 corresponding to the first CHO configuration information satisfies the CHO execution conditions and cell1 corresponding to the second CHO configuration information also satisfies the CHO execution conditions, then UE1 can determine that it is in the first area based on its own geographical location. The first area corresponds to PLMN1 and the first CHO configuration information. Since the PLMN and / or AMF that supports / allows UE1 to access in the first area is PLMN1 and / or AMF1, UE1 can determine cell1 corresponding to the first CHO configuration information as the target cell, PLMN1 as the target PLMN, and AMF1 as the target AMF. Optionally, UE1 can also determine the first area as the target area.

[0161] For another example, assuming that UE2 supports PLMN1 and PLMN2, if UE2 determines the CHO execution condition and determines that the cell1 corresponding to the second CHO configuration information meets the CHO execution condition information, UE2 can determine that it is in the second area based on its own geographical location. Since the PLMN and / or AMF that supports / allows UE2 to access in the second area is PLMN2 and / or AMF2, UE2 can determine the cell1 corresponding to the second CHO configuration information as the target cell, determine PLMN2 as the target PLMN, and determine AMF2 as the target AMF.

[0162] For another example, assuming that UE2 supports PLMN1 and PLMN2, if UE2 determines that cell1 corresponding to the first CHO configuration information satisfies the CHO execution condition information and cell1 corresponding to the second CHO configuration information also satisfies the CHO execution condition information after judging the CHO execution condition, UE2 can determine that it is in the second area based on its own geographical location. Since the PLMN and / or AMF that supports / allows UE2 to access in the second area is PLMN2 and / or AMF2, UE2 can determine cell1 corresponding to the second CHO configuration information as the target cell, PLMN2 as the target PLMN, and AMF2 as the target AMF. Optionally, UE2 can also determine the second area as the target area.

[0163] Step S504: The terminal device sends a first message to the target network device. The first message is used to indicate that the terminal device has successfully switched to the target cell. The first message includes target PLMN information and / or target AMF information.

[0164] Correspondingly, the target network device may receive the first message from the terminal device.

[0165] It is understood that in the embodiments of the present application, the network device that manages the candidate target cell is referred to as the candidate target network device, or in other words, the network device to which the candidate target cell belongs is referred to as the candidate target network device. After the terminal device determines the candidate target cell as the target cell, the candidate target network device can be referred to as the target network device, that is, the target network device is the network device to which the candidate target cell determined as the target cell belongs.

[0166] The target cell supports the first PLMN and / or the first AMF, and supports the second PLMN and / or the second AMF; or, the target cell accesses the first PLMN and / or the first AMF, and accesses the second PLMN and / or the second AMF; or, the target cell belongs to the first PLMN, and the core network device connected to the target cell is the first AMF, and the target cell also belongs to the second PLMN, and the core network device connected to the target cell is the second AMF; or, the target cell is managed by the first PLMN and / or the first AMF, and is managed by the second PLMN and / or the second AMF. Accordingly, the target PLMN information and / or the target AMF information can be the first PLMN information and / or the first AMF information, or the second PLMN information and / or the second AMF information.

[0167] Optionally, the first message may also include one or more of the following information: identification information of the target cell (such as PCI and / or C-RNTI, or CGI), index information corresponding to the target cell (such as the measurement identifier (measID) corresponding to the target cell and / or the CHO configuration identifier (CondReconfigId) corresponding to the target cell), other information in the CHO configuration information corresponding to the target PLMN or target AMF except the index information and identification information corresponding to the target cell, and area information corresponding to the target PLMN or target AMF.

[0168] Exemplarily, the first cell is a candidate target cell, and the first cell may be one of multiple candidate target cells configured by the source network device for the terminal device. If the terminal device determines the first cell as the target cell, and determines the first PLMN to which the first cell belongs as the target PLMN, and / or determines the first AMF that manages the first cell as the target AMF, the terminal device may send a first message to the network device to which the first cell belongs (i.e., the target network device), and the first message includes at least one of the following: the first PLMN information, the first AMF information, the identification information of the first cell (such as the PCI and / or C-RNTI of the first cell, or CGI), and one or more of the first CHO configuration information of the first cell, and the first CHO configuration information includes the index information corresponding to the first cell (such as the measurement identifier measID and / or the CHO configuration identifier CondReconfigId), the first PLMN information or the area information corresponding to the first AMF information.

[0169] It can be understood that the network device to which the first cell belongs can be called a candidate target network device before the first cell is determined as the target cell, and after the first cell is determined as the target cell, the network device to which the first cell belongs can be called a target network device.

[0170] Optionally, the first message may be a handover confirmation (such as HO confirm) message, or have other names, which is not limited in this application.

[0171] As mentioned above, the key information / parameters for accessing the candidate target cell included in the first CHO configuration information may be the same as or different from the key information / parameters for accessing the candidate target cell included in the second CHO configuration information, and the RACH resource information included in the first CHO configuration information may be the same as or different from the RACH resource information included in the second CHO configuration information.

[0172] If the key information / parameters for accessing the candidate target cell included in the first CHO configuration information are different from the key information / parameters for accessing the candidate target cell (i.e., the target cell) included in the second CHO configuration information, then when the RACH resource information included in the first CHO configuration information is different from the RACH resource information included in the second CHO configuration information, for example, the preamble codes may be different and / or the time-frequency resources may be different, if the terminal device determines the candidate target cell as the target cell, and determines the first PLMN as the target PLMN, and determines the first AMF as the target AMF, then when the terminal device sends a first message to the network device (i.e., the target network device) to which the candidate target cell belongs, the first key corresponding to the first CHO configuration information may be used to encrypt the first message, thereby effectively improving the security of the transmission of the first message. Optionally, the first CHO configuration information may include first key information, and the terminal device may determine the first key based on the first key information.

[0173] Correspondingly, since different CHO configuration information corresponds to different RACH resource information, or different PLMN information and / or AMF information corresponds to different RACH resource information, after the target network device receives the first message, it can determine that the terminal device selects the first CHO configuration information based on the RACH resource used when the terminal device initiates random access, or determine that the target PLMN selected by the terminal device is the first PLMN or the selected target AMF is the first AMF, and then use the corresponding first key to decrypt the first message. The first key may be the key indicated by the first key information in the first CHO configuration information.

[0174] When the RACH resource information included in the first CHO configuration information is the same as the RACH resource information included in the second CHO configuration information, the target network device cannot determine which key the terminal device uses based on the RACH resource used when the terminal device initiates random access. In this scenario, to enable the target network device to correctly receive / parse the first message, the terminal device can send two first messages to the target network device, one of which is encrypted using the first key corresponding to the first CHO configuration information, and the other is encrypted using the second key corresponding to the second CHO configuration information. This effectively improves the security of the transmission of the first message. Optionally, the first CHO configuration information can include first key information, and the second CHO configuration information can include second key information. The terminal device can determine the first key based on the first key information and the second key based on the second key information. Accordingly, after receiving the two first messages, the target network device can decrypt the two first messages using the first key and / or decrypt the two first messages using the second key. It can be seen that in this scenario, regardless of whether the terminal device encrypts the first message using the first key or the second key, the target network device can decrypt the first message and obtain the information therein.

[0175] Optionally, in a possible implementation, when the RACH resource information included in different CHO configuration information is the same, the terminal device may also use the key corresponding to the first CHO configuration information or the key corresponding to the second CHO configuration information to encrypt the first message. Although the RACH resource information included in different CHO configuration information is the same, the target network device cannot determine the key for encrypting the first message based on the RACH resource information used by the terminal device when performing random access. However, since the terminal device uses the key corresponding to one of the CHO configuration information to encrypt the first message, the target network device can use the secret keys corresponding to different CHO configuration information (i.e., the key corresponding to the first CHO configuration information and the key corresponding to the second CHO configuration information) to perform a decryption attempt, and thus, the target network device can successfully decrypt the first message.

[0176] Optionally, after receiving the first message from the terminal device, the target network device may send a second message to the target AMF, where the second message is used to notify the target AMF that the terminal device has completed the handover. The second message may be a handover notification (HOnotify) message or have other names, which is not limited in this application. For example, since it has been assumed above that the terminal device is located in the first area and meets the CHO execution conditions corresponding to the first PLMN and / or the first AMF, the first PLMN and / or the first AMF correspond to the first area, and the terminal device supports the first PLMN and / or the first AMF. Therefore, the target AMF here may refer to the first AMF.

[0177] Optionally, since the target cell or target network device can be managed by multiple AMFs (such as the first AMF and the second AMF described above), after the target network device receives the first message from the terminal device, the target network device can determine the target AMF selected by the terminal device based on the first message. If the target network device determines that the target AMF is the first AMF, the target network device can send a third message to the second AMF, and the third message is used to instruct the second AMF to release the connection established by the second AMF for the terminal device, and the connection refers to the connection between the second AMF and the target network device established by the second AMF for the terminal device. The third message may include a connection release reason value, for example, the connection release reason value is used to indicate that the connection release reason is a location abnormality or AMF unavailability. Here, the second AMF refers to an AMF or a non-target AMF that is used to manage the target network device but does not allow the terminal device to access.

[0178] Optionally, after the terminal device determines the first PLMN as the target PLMN and the first AMF as the target AMF, the terminal device may also release the second PLMN information and / or the second AMF information, as well as the second CHO configuration information and the second area information. Alternatively, the target network device may also send a fourth message to the terminal device, where the fourth message is used to instruct the terminal device to release the second PLMN information and / or the second AMF information, as well as the corresponding second CHO configuration information and the second area information. Accordingly, after receiving the fourth message, the terminal device may release the second PLMN information and / or the second AMF information, as well as the second CHO configuration information and the second area information. Through this solution, the terminal device can promptly delete or release unnecessary configuration information or resources, thereby effectively improving resource utilization.

[0179] It should be understood that the embodiment of the present application is illustrated by taking the first AMF and the second AMF as an example. When the target cell or target network device is managed by more AMFs, the target network device can send a third message to each AMF except the target AMF to instruct these AMFs to release the connection established for the terminal device.

[0180] As can be seen, the above technical solution provides a CHO mechanism when cells covering geographical areas of multiple countries or service areas of multiple operators are configured as candidate target cells for a terminal device. Because the terminal device can determine the target cell, target PLMN, and / or target AMF from the configured candidate target cells based on cells that meet the CHO execution conditions, its own location, and the PLMNs and / or AMFs it supports, the above technical solution can effectively improve the reliability of handover.

[0181] Please refer to Figure 9 , which is a specific example of a communication method provided in an embodiment of the present application. In this example, S-gNB represents the source base station, S-AMF represents the source AMF, T-gNB represents the target base station, which can also be called candidate T-gNB, T-AMF1 represents the target AMF1, and T-AMF2 represents the target AMF2. The S-gNB can configure a cell under the T-gNB as a candidate target cell of the UE. For the candidate target cell, T-AMF1 is the AMF that manages the virtual cell corresponding to PLMN1 in the candidate target cell, and T-AMF2 is the AMF that manages the virtual cell corresponding to PLMN2 in the candidate target cell, that is, the candidate target cell is a cell that supports PLMN1 and PLMN2, or the candidate target cell is a cell that supports T-AMF1 and T-AMF2. In other words, the core network device that the candidate target cell can connect to is T-AMF1 and / or T-AMF2, and the candidate target cell belongs to PLMN1 and / or PLMN2. Alternatively, the candidate target cell is managed by T-AMF1 / T-AMF2 / PLMN1 / PLMN2. Figure 9As shown, in step S901-a, the S-gNB performs CHO preparation with the T-gNB through the S-AMF and T-AMF1. Similarly, in step S901-b, the S-gNB performs CHO preparation with the T-gNB through the S-AMF and T-AMF2. In step S902-a, the S-gNB may send first CHO configuration information to the UE, where the first CHO configuration information includes first CHO execution condition information. Similarly, in step S902-b, the S-gNB may send second CHO configuration information to the UE, where the second CHO configuration information includes second CHO execution condition information. The first CHO configuration information and the second CHO configuration information may be sent in the same RRC message or in different RRC messages, without limitation. In step S903, the UE may determine whether the CHO execution condition is met based on the first CHO configuration information and the second CHO configuration information. If the UE is located in the area corresponding to PLMN1, the UE supports PLMN1, and the first CHO execution condition is met, the UE can determine that the candidate target cell is the target cell, and determine that PLMN1 is the target PLMN and T-AMF1 is the target AMF. Furthermore, in step S904, the UE can send a handover confirmation message to the T-gNB. The handover notification message is used to notify the T-gNB that the UE has successfully switched to the target cell. The handover confirmation message includes target PLMN information and / or AMF information (i.e., PLMN1 information and / or T-AMF1 information). Subsequently, in step S905, the T-gNB can send a handover notification message to T-AMF1. The handover notification message is used to notify T-AMF1 that the UE has completed the handover. In step S906, the T-gNB may send a connection release message to the T-AMF2 (i.e., non-target AMF). The connection release message is used to instruct the T-AMF2 to release the connection between the T-AMF2 and the T-gNB established for the UE. The connection release message includes the reason for the connection release, such as abnormal location, unavailability of T-AMF2, or mismatch between the T-AMF2 and UE locations.

[0182] It should be noted that Figure 9 The T-AMF1 and S-AMF shown in the figure can be the same or different, and the T-AMF2 and S-AMF can be the same or different, without limitation. It should be noted that T-AMF1 and T-AMF2 are different. The S-gNB and T-gNB can be the same base station or different base stations, which is not limited in this embodiment of the application.

[0183] Optionally, the target network device in the embodiment of the present application may be in a separate form including a CU node and a DU node. Specifically, if the target network device is in a separate form including a CU node and a DU node, the CU node as the message / information receiver may send part or all of the received information to the DU node. For example, the target CU node may send part or all of the information contained in the received first message to the target DU node. The target CU node is the CU node of the target network device, and the target DU node is the DU node of the target network device. The information contained in the first message can be referred to the description above and will not be repeated here.

[0184] Furthermore, if the CU node can be divided into a control plane (CU-CP) and a user plane (CU-UP), the CU-CP node as the message / information receiver can send part or all of the received information to the CU-UP node. For example, the target CU-CP node can send part or all of the information contained in the received first message to the target CU-UP node.

[0185] Optionally, the terminal device in the embodiment of the present application may be in a separate form including a CU node and a DU node. Furthermore, the CU node in the terminal device may also be divided into a control plane (CU-CP) and a user plane (CU-UP). Specifically, if the terminal device is in a separate form including a CU node and a DU node, or further the CU node of the terminal device includes a control plane (CU-CP) and a user plane (CU-UP), then the CU node (or CU-CP node) as the message / information receiver may send part or all of the received information to the DU node (or CU-UP node). For the specific implementation method, please refer to the description above and will not be repeated here.

[0186] It can be seen that the above technical solution provides an information interaction method in the CU-DU scenario, which enables the sending / receiving nodes to exchange information reasonably and timely, ensures the normal progress of the CHO process, and improves system reliability.

[0187] The present application also provides a communication device, please refer to Figure 10 , is a structural diagram of a communication device provided in an embodiment of the present application, the communication device 1000 includes: a transceiver module 1010 and a processing module 1020.

[0188] In one embodiment, the communication device can be used to implement the functions of the terminal device in any of the above method embodiments. For example, the communication device can be a terminal device, such as a handheld terminal device or an in-vehicle terminal device. The communication device can also be a chip or circuit included in the terminal device, or a device including the terminal device, such as various types of vehicles.

[0189] For example, when the communication device executes Figure 5 When the operation or steps of the terminal device correspond to the method embodiment shown in , the transceiver module 1010 is used to receive first information of the candidate target cell from the source network device, the first information including first PLMN information and / or first AMF information, and second PLMN information and / or second AMF information; wherein, the first information also includes first CHO configuration information and first area information corresponding to the first PLMN information and / or first AMF information, and second CHO configuration information and second area information corresponding to the second PLMN information and / or second AMF information, the first area information is used to indicate the first area covered by the candidate target cell, and the second area information is used to indicate the second area covered by the candidate target cell; the processing module 1020 is used to determine the target cell and target PLMN information and / or target AMF information based on the first information and the area where it is currently located.

[0190] In one possible design, the processing module 1020 is specifically used to, if the first CHO execution condition in the first CHO configuration information is met and the terminal device is currently located in the first area, the terminal device can determine the candidate target cell as the target cell, and determine the first PLMN information as the target PLMN information, and / or determine the first AMF information as the target AMF information.

[0191] In one possible design, the processing module 1020 is specifically used to, if the first CHO execution condition in the first CHO configuration information and the second CHO execution condition in the second CHO configuration information are both met, and the terminal device is currently located in the first area, then the terminal device can determine that the candidate target cell is the target cell, and determine the first PLMN information as the target PLMN information, and / or determine the first AMF information as the target AMF information.

[0192] In one possible design, the transceiver module 1010 is also used to send a first message to the target network device, where the first message is used to indicate that the terminal device has successfully switched to the target cell. The first message includes target PLMN information and / or target AMF information, and the target network device is a network device that manages the target cell.

[0193] In one possible design, the first message also includes identification information of the target cell and index information corresponding to the target cell.

[0194] In one possible design, when the RACH resource information included in the first CHO configuration information is different from the RACH resource information included in the second CHO configuration information, the first message may be encrypted using a first key corresponding to the first CHO configuration information.

[0195] In one possible design, when the RACH resource information included in the first CHO configuration information is the same as the RACH resource information included in the second CHO configuration information, the transceiver module 1010 is specifically used to send two first messages to the target network device, wherein one first message is encrypted using a first key corresponding to the first CHO configuration information, and the other first message is encrypted using a second key corresponding to the second CHO configuration information.

[0196] In one possible design, the first CHO configuration information includes first CHO execution condition information, which is used to indicate the first CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the first PLMN information includes the identifier of the first PLMN, the first AMF information includes the identifier of the first AMF, or includes the identifier of the first AMF and the identifier of the first PLMN; the second CHO configuration information includes second CHO execution condition information, which is used to indicate the second CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the second PLMN information includes the identifier of the second PLMN, the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

[0197] In one possible design, the processing module 1020 is further configured to release the second PLMN information and / or the second AMF information, as well as the second CHO configuration information and the second area information. In another embodiment, the communication device may be configured to implement the functions of a network device (e.g., a source network device or a target network device (or candidate target network device)) in any of the above method embodiments. For example, the communication device may be a network device or a chip or circuit included in the network device.

[0198] For example, when the communication device executes Figure 5When the operation or step of the source network device corresponds to the method embodiment shown in , the transceiver module 1010 is used to receive first information of the candidate target cell from the candidate target network device, the first information including first PLMN information and / or first AMF information, and second PLMN information and / or second AMF information; wherein, the first information also includes first CHO configuration information and first area information corresponding to the first PLMN information and / or first AMF information, and second CHO configuration information and second area information corresponding to the second PLMN information and / or second AMF information, the first area information is used to indicate the first area covered by the candidate target cell, and the second area information is used to indicate the second area covered by the candidate target cell; the processing module 1020 is used to send the first information of the candidate target cell to the terminal device through the transceiver module 1020.

[0199] In one possible design, the first CHO configuration information includes first CHO execution condition information, which is used to indicate the first CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the first PLMN information includes the identifier of the first PLMN, the first AMF information includes the identifier of the first AMF, or includes the identifier of the first AMF and the identifier of the first PLMN; the second CHO configuration information includes second CHO execution condition information, which is used to indicate the second CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the second PLMN information includes the identifier of the second PLMN, the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

[0200] When the communication device executes Figure 5In the method embodiment shown in , when the operation or step of the target network device corresponds to the operation or step of the target network device, the transceiver module 1010 is used to send first information of the candidate target cell to the source network device, the first information including first PLMN information and / or first AMF information, and second PLMN information and / or second AMF information; wherein the first information also includes first CHO configuration information and first area information corresponding to the first PLMN information and / or first AMF information, and second CHO configuration information and second area information corresponding to the second PLMN information and / or second AMF information, the first area information is used to indicate the first area covered by the candidate target cell, and the second area information is used to indicate the second area covered by the candidate target cell; if the terminal device determines that the candidate target cell is the target cell, the processing module 1020 is used to receive a first message from the terminal device through the transceiver module 1010, the first message being used to indicate that the terminal device has successfully switched to the target cell, the first message including target PLMN information and / or target AMF information, the target PLMN information and / or target AMF information being the first PLMN information and / or first AMF information, or the second PLMN information and / or second AMF information.

[0201] In one possible design, when the RACH resource information included in the first CHO configuration information is different from the RACH resource information included in the second CHO configuration information, the processing module 1020 is specifically used to determine a first key for decrypting the first message based on the RACH resource information used by the terminal device to initiate a random access process, and use the first key to decrypt the first message.

[0202] In one possible design, when the RACH resource information included in the first CHO configuration information is the same as the RACH resource information included in the second CHO configuration information, the transceiver module 1010 is specifically used to receive two first messages from the terminal device, and the processing module 1020 is specifically used to decrypt the two first messages using a first key, and / or decrypt the two first messages using a second key; wherein the first key is a key corresponding to the first CHO configuration information, and the second key is a key corresponding to the second CHO configuration information.

[0203] In one possible design, the transceiver module 1010 is also used to send a second message to the target AMF corresponding to the target AMF information, and the second message is used to indicate to the target AMF that the terminal device has completed the switching.

[0204] In one possible design, the transceiver module 1010 is also used to send a third message to the AMF corresponding to another AMF information other than the target AMF information in the first AMF information and the second AMF information, where the third message is used to instruct the other AMF to release the connection established for the terminal device.

[0205] In one possible design, the third message includes a connection release reason value, which is a location abnormality or AMF unavailable.

[0206] In one possible design, the first CHO configuration information includes first CHO execution condition information, which is used to indicate the CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the first PLMN information includes the identifier of the first PLMN, the first AMF information includes the identifier of the first AMF, or includes the identifier of the first AMF and the identifier of the first PLMN; the second CHO configuration information includes second CHO execution condition information, which is used to indicate the CHO execution condition corresponding to the target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, or execution condition information based on time / timer, or execution condition information based on location; the second PLMN information includes the identifier of the second PLMN, the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

[0207] The processing module 1020 involved in the communication device can be implemented by at least one processor or processor-related circuit components, and the transceiver module 1010 can be implemented by at least one transceiver or transceiver-related circuit components or communication interfaces. The operations and / or functions of each module in the communication device are respectively to achieve Figure 5 、 Figure 7 、 Figure 8 or Figure 9 For the sake of brevity, the corresponding process of the method shown in FIG. is not repeated here. Optionally, the communication device may further include a storage module, which can be used to store data and / or instructions. The transceiver module 1010 and / or the processing module 1020 can read the data and / or instructions in the access module, thereby enabling the communication device to implement the corresponding method. The storage module can be implemented, for example, by at least one memory.

[0208] The above-mentioned storage module, processing module and transceiver module may exist separately, or all or part of the modules may be integrated, for example, the storage module and the processing module are integrated, or the processing module and the transceiver module are integrated.

[0209] Please refer to Figure 11 , is another structural diagram of a communication device provided in an embodiment of the present application. The communication device can be used to implement the functions corresponding to the terminal device in the above-mentioned method embodiment, for example, it can be a terminal device or a device that can support the terminal device to implement the corresponding functions in the above-mentioned method embodiment. Alternatively, the communication device can also be used to implement the functions corresponding to the source network device or the target network device in the above-mentioned method embodiment, for example, it can be a source network device or the target network device, or a device that can support the source network device or the target network device to implement the corresponding functions in the above-mentioned method embodiment.

[0210] The communication device 1100 may include a processor 1101, a communication interface 1102, and a memory 1103. The communication interface 1102 is used to communicate with other devices via a transmission medium. The communication interface 1102 may be a transceiver or an interface circuit such as a transceiver circuit, a transceiver chip, etc. The memory 1103 is used to store program instructions and / or data, and the processor 1101 is used to execute the program instructions stored in the memory 1103, thereby implementing the method in the above-mentioned method embodiment. Optionally, the memory 1103 and the processor 1101 are coupled, and the coupling is an indirect coupling or communication connection between devices, units or modules, which can be electrical, mechanical or other forms, and is used for information exchange between devices, units or modules.

[0211] In one embodiment, the communication interface 1102 may be specifically used to execute the actions of the above-mentioned transceiver module 1010, and the processor 1101 may be specifically used to execute the actions of the above-mentioned processing module 1020, which will not be described in detail in this application.

[0212] The specific connection medium between the communication interface 1102, the processor 1101 and the memory 1103 is not limited in the embodiment of the present application. Figure 11 The memory 1103, the processor 1101 and the communication interface 1102 are connected via a bus 1104. Figure 11 The connections between the other components are shown in bold lines, which are only for illustration and are not intended to be limiting. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, Figure 11 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0213] Please refer to Figure 12, shows a simplified structural diagram of a communication device, which can be a terminal device specifically for implementing the functions of the terminal device involved in any of the above method embodiments. Figure 12 In this article, we take mobile phones as an example of terminal devices. Figure 12 As shown, the terminal device includes a processor and may also include a memory. Of course, it may also include a radio frequency circuit, an antenna, and input and output devices. The processor is mainly used to process communication protocols and communication data, as well as to control the terminal device, execute software programs, and process software program data. The memory is mainly used to store software programs and data. The radio frequency circuit is mainly used for converting baseband signals into radio frequency signals and processing radio frequency signals. The antenna is mainly used to transmit and receive radio frequency signals in the form of electromagnetic waves. Input and output devices, such as touch screens, display screens, keyboards, etc., are mainly used to receive data input by the user and output data to the user. It should be noted that some types of terminal devices may not have input and output devices.

[0214] When data needs to be sent, the processor performs baseband processing on the data to be sent and outputs the baseband signal to the RF circuit. The RF circuit performs RF processing on the baseband signal and then transmits the RF signal to the outside in the form of electromagnetic waves through the antenna. When data is sent to the terminal device, the RF circuit receives the RF signal through the antenna, converts the RF signal into a baseband signal, and outputs the baseband signal to the processor. The processor converts the baseband signal into data and processes the data. For the sake of explanation, Figure 12 Only one memory and processor are shown. In actual terminal device products, one or more processors and one or more memories may exist. Memory may also be referred to as a storage medium or storage device. The memory may be provided independently of the processor or integrated with the processor, and this is not limited in the embodiments of the present application.

[0215] In the embodiment of the present application, the antenna and radio frequency circuit with transceiver functions can be regarded as the transceiver unit of the terminal device, and the processor with processing function can be regarded as the processing unit of the terminal device. Figure 12As shown, the terminal device includes a transceiver unit 1210 and a processing unit 1220. The transceiver unit may also be referred to as a transceiver, transceiver, transceiver device, etc. The processing unit may also be referred to as a processor, processing board, processing module, processing device, etc. Optionally, the device in the transceiver unit 1210 that implements the receiving function may be considered a receiving unit, and the device in the transceiver unit 1210 that implements the transmitting function may be considered a transmitting unit, i.e., the transceiver unit 1210 includes a receiving unit and a transmitting unit. The transceiver unit may also be sometimes referred to as a transceiver, transceiver, or transceiver circuit. The receiving unit may also be sometimes referred to as a receiver, receiver, or receiving circuit. The transmitting unit may also be sometimes referred to as a transmitter, transmitter, or transmitting circuit. It should be understood that the transceiver unit 1210 is used to perform the transmitting and receiving operations on the terminal device side in the above-described method embodiments, and the processing unit 1220 is used to perform other operations on the terminal device in addition to the transmitting and receiving operations in the above-described method embodiments.

[0216] Please refer to Figure 13 , shows a structural schematic diagram of another simplified communication device, which can be specifically a network device, such as a base station, used to implement the functions of the network device (such as the source network device or the target network device or the candidate target network device) involved in any of the above method embodiments.

[0217] The network device 1300 includes one or more DUs 1301 and one or more CUs 1302. The DU 1301 may include at least one antenna 13011, at least one radio frequency unit 13012, at least one processor 13013, and at least one memory 13014. The DU 1301 is primarily used for transmitting and receiving radio frequency signals, converting radio frequency signals into baseband signals, and performing some baseband processing.

[0218] The CU 1302 may include at least one processor 13022 and at least one memory 13021. The CU 1302 is mainly used to perform baseband processing, control the base station, etc. The CU 1302 is the control center of the base station, and may also be called a processing unit. For example, the CU 1302 may be used to control the base station to perform the above Figure 5 、 Figure 7 、 Figure 8 or Figure 9 The operations or steps corresponding to the source network device or the target network device in the method shown.

[0219] The CU 1302 and the DU 1301 can communicate through an interface, wherein the control plane (CP) interface can be Fs-C, such as F1-C, and the user plane (UP) interface can be Fs-U, such as F1-U. The DU 1301 and the CU 1302 can be physically set together or physically separated (i.e., a distributed base station), without limitation.

[0220] Specifically, baseband processing on the CU and DU can be divided according to the protocol layers of the wireless network. For example, the functions of the PDCP layer and above are set in the CU, and the functions of the protocol layers below the PDCP layer (such as the RLC layer and MAC layer) are set in the DU. For another example, the CU implements the functions of the RRC and PDCP layers, and the DU implements the functions of the RLC, MAC, and physical (PHY) layers.

[0221] Optionally, the base station 1300 may include one or more radio frequency units (RUs), one or more DUs, and one or more CUs. The DU may include at least one processor 13013 and at least one memory 13014, the RU may include at least one antenna 13011 and at least one radio frequency unit 13012, and the CU may include at least one processor 13022 and at least one memory 13021.

[0222] In one embodiment, the CU 1302 can be composed of one or more single boards, and multiple single boards can jointly support a wireless access network with a single access indication (such as a 5G network), or respectively support wireless access networks with different access standards (such as an LTE network, a 5G network, or other networks). The memory 13021 and the processor 13022 can serve one or more single boards. That is, a memory and a processor can be set separately on each single board. It is also possible that multiple single boards share the same memory and processor. In addition, necessary circuits can be set on each single board. The DU 1301 can be composed of one or more single boards, and multiple single boards can jointly support a wireless access network with a single access indication (such as a 5G network), or respectively support wireless access networks with different access standards (such as an LTE network, a 5G network, or other networks). The memory 13014 and the processor 13013 can serve one or more single boards. That is, a memory and a processor can be set separately on each single board. It is also possible that multiple single boards share the same memory and processor. In addition, necessary circuits can be set on each single board.

[0223] An embodiment of the present application also provides a chip system, comprising: a processor, the processor being coupled to a memory, the memory being used to store programs or instructions, and when the programs or instructions are executed by the processor, the chip system implements the method of the corresponding terminal device or the method of the corresponding network device (such as a source network device or a target network device) in any of the above method embodiments.

[0224] Optionally, there may be one or more processors in the chip system. The processor may be implemented in hardware or software. When implemented in hardware, the processor may be a logic circuit, an integrated circuit, etc. When implemented in software, the processor may be a general-purpose processor implemented by reading software code stored in a memory.

[0225] Optionally, the memory in the chip system may be one or more memories. The memory may be integrated with the processor or may be provided separately from the processor, which is not limited in this application. For example, the memory may be a non-transient processor, such as a read-only memory (ROM), which may be integrated with the processor on the same chip or provided on different chips. This application does not specifically limit the type of memory or the configuration of the memory and the processor.

[0226] Exemplarily, the chip system can be a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), a system on chip (SoC), a central processor unit (CPU), a network processor (NP), a digital signal processor (DSP), a microcontroller unit (MCU), a programmable logic device (PLD) or other integrated chips.

[0227] It should be understood that each step in the above method embodiment can be completed by hardware integrated logic circuits in a processor or by software instructions. The method steps disclosed in the embodiments of the present application can be directly embodied as being executed by a hardware processor, or by a combination of hardware and software modules in a processor.

[0228] An embodiment of the present application further provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer-readable instructions. When a computer reads and executes the computer-readable instructions, the computer executes the method in any of the above method embodiments.

[0229] An embodiment of the present application further provides a computer program product. When a computer reads and executes the computer program product, the computer executes the method in any of the above method embodiments.

[0230] An embodiment of the present application further provides a communications system, comprising a source network device and a target network device. Optionally, the communications system may further comprise at least one terminal device. In a CHO handover scenario, before the terminal device determines to handover to the target network device, the target network device may be a candidate target network device configured by the source network device. Optionally, the communications system may further comprise one or more other candidate target network devices configured by the source network device. Optionally, the communications system may further comprise a core network device.

[0231] It should be understood that the processor mentioned in the embodiments of the present application may be a CPU, or may be other general-purpose processors, DSPs, ASICs, FPGAs or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0232] It should also be understood that the memory mentioned in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct rambus RAM (DR RAM).

[0233] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, the memory (storage module) is integrated into the processor.

[0234] It should be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0235] It should be understood that the various numerical numbers involved in the various embodiments of the present application are only for the convenience of description. The size of the serial numbers of the above-mentioned processes or steps does not mean the order of execution. The execution order of each process or step should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0236] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0237] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0238] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0239] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0240] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0241] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a ROM, a RAM, a magnetic disk, or an optical disk.

[0242] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

Claims

1. A communication method, characterized in that: The method comprises: receiving first information of a candidate target cell from a source network device, the first information including first public land mobile network (PLMN) information and / or first access and mobility management function (AMF) information, and second PLMN information and / or second AMF information; wherein the first information further includes first conditional handover (CHO) configuration information and first area information corresponding to the first PLMN information and / or the first AMF information, and second CHO configuration information and second area information corresponding to the second PLMN information and / or the second AMF information, the first area information being used to indicate a first area covered by the candidate target cell, and the second area information being used to indicate a second area covered by the candidate target cell; Determine the target cell and target PLMN information and / or target AMF information based on the first information and the area where the terminal device is currently located.

2. The method according to claim 1, characterized in that The determining, based on the first information and the area where the terminal device is currently located, target cell and target PLMN information and / or target AMF information includes: If the first CHO execution condition in the first CHO configuration information is met and the terminal device is currently located in the first area, the terminal device determines that the candidate target cell is the target cell, and determines that the first PLMN information is the target PLMN information, and / or determines that the first AMF information is the target AMF information.

3. The method according to claim 1 or 2, characterized in that The determining, based on the first information and the area where the terminal device is currently located, target cell and target PLMN information and / or target AMF information includes: If the first CHO execution condition in the first CHO configuration information and the second CHO execution condition in the second CHO configuration information are both met, and the terminal device is currently located in the first area, the terminal device determines that the candidate target cell is the target cell, and determines that the first PLMN information is the target PLMN information, and / or determines that the first AMF information is the target AMF information.

4. The method according to claim 1 or 2, characterized in that After the terminal device successfully switches to the target cell, the method further includes: A first message is sent to the target network device, where the first message is used to indicate that the terminal device has successfully switched to the target cell, and the first message includes the target PLMN information and / or the target AMF information. The target network device is a network device that manages the target cell.

5. The method according to claim 4, characterized in that The first message also includes identification information of the target cell and index information corresponding to the target cell.

6. The method according to claim 3, characterized in that After the terminal device successfully switches to the target cell, the method further includes: A first message is sent to the target network device, where the first message is used to indicate that the terminal device has successfully switched to the target cell, and the first message includes the target PLMN information and / or the target AMF information. The target network device is a network device that manages the target cell.

7. The method according to claim 6, characterized in that The first message also includes identification information of the target cell and index information corresponding to the target cell.

8. The method according to claim 4, characterized in that When the random access channel RACH resource information included in the first CHO configuration information is different from the RACH resource information included in the second CHO configuration information, the first message is encrypted using a first key corresponding to the first CHO configuration information.

9. The method according to any one of claims 5 to 7, characterized in that When the random access channel RACH resource information included in the first CHO configuration information is different from the RACH resource information included in the second CHO configuration information, the first message is encrypted using a first key corresponding to the first CHO configuration information.

10. The method according to claim 4, characterized in that When the RACH resource information included in the first CHO configuration information is the same as the RACH resource information included in the second CHO configuration information, the sending the first message to the target network device includes: Two first messages are sent to the target network device, wherein one of the first messages is encrypted using a first key corresponding to the first CHO configuration information, and the other first message is encrypted using a second key corresponding to the second CHO configuration information.

11. The method according to any one of claims 5 to 7, characterized in that When the RACH resource information included in the first CHO configuration information is the same as the RACH resource information included in the second CHO configuration information, the sending the first message to the target network device includes: Two first messages are sent to the target network device, wherein one of the first messages is encrypted using a first key corresponding to the first CHO configuration information, and the other first message is encrypted using a second key corresponding to the second CHO configuration information.

12. The method according to any one of claims 1, 2, 5 to 8, and 10, characterized in that The first CHO configuration information includes first CHO execution condition information, where the first CHO execution condition information is used to indicate a first CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The first PLMN information includes an identifier of the first PLMN, and the first AMF information includes an identifier of the first AMF, or includes the identifier of the first AMF and an identifier of the first PLMN; The second CHO configuration information includes second CHO execution condition information, where the second CHO execution condition information is used to indicate a second CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The second PLMN information includes the identifier of the second PLMN, and the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

13. The method according to claim 3, characterized in that The first CHO configuration information includes first CHO execution condition information, where the first CHO execution condition information is used to indicate a first CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The first PLMN information includes an identifier of the first PLMN, and the first AMF information includes an identifier of the first AMF, or includes the identifier of the first AMF and an identifier of the first PLMN; The second CHO configuration information includes second CHO execution condition information, where the second CHO execution condition information is used to indicate a second CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The second PLMN information includes the identifier of the second PLMN, and the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

14. The method according to claim 4, characterized in that The first CHO configuration information includes first CHO execution condition information, where the first CHO execution condition information is used to indicate a first CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The first PLMN information includes an identifier of the first PLMN, and the first AMF information includes an identifier of the first AMF, or includes the identifier of the first AMF and an identifier of the first PLMN; The second CHO configuration information includes second CHO execution condition information, where the second CHO execution condition information is used to indicate a second CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The second PLMN information includes the identifier of the second PLMN, and the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

15. The method according to claim 9, characterized in that The first CHO configuration information includes first CHO execution condition information, where the first CHO execution condition information is used to indicate a first CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The first PLMN information includes an identifier of the first PLMN, and the first AMF information includes an identifier of the first AMF, or includes the identifier of the first AMF and an identifier of the first PLMN; The second CHO configuration information includes second CHO execution condition information, where the second CHO execution condition information is used to indicate a second CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The second PLMN information includes the identifier of the second PLMN, and the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

16. The method according to claim 11, characterized in that The first CHO configuration information includes first CHO execution condition information, where the first CHO execution condition information is used to indicate a first CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The first PLMN information includes an identifier of the first PLMN, and the first AMF information includes an identifier of the first AMF, or includes the identifier of the first AMF and an identifier of the first PLMN; The second CHO configuration information includes second CHO execution condition information, where the second CHO execution condition information is used to indicate a second CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The second PLMN information includes the identifier of the second PLMN, and the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

17. The method according to any one of claims 1, 2, 5 to 8, 10, 13 to 16, characterized in that The method further comprises: Release the second PLMN information and / or the second AMF information, and release the second CHO configuration information and the second area information.

18. The method according to claim 3, characterized in that The method further comprises: Release the second PLMN information and / or the second AMF information, and release the second CHO configuration information and the second area information.

19. The method according to claim 4, characterized in that The method further comprises: Release the second PLMN information and / or the second AMF information, and release the second CHO configuration information and the second area information.

20. The method according to claim 9, characterized in that The method further comprises: Release the second PLMN information and / or the second AMF information, and release the second CHO configuration information and the second area information.

21. The method according to claim 11, wherein The method further comprises: Release the second PLMN information and / or the second AMF information, and release the second CHO configuration information and the second area information.

22. The method according to claim 12, wherein: The method further comprises: Release the second PLMN information and / or the second AMF information, and release the second CHO configuration information and the second area information.

23. A communication method, characterized in that: The method comprises: receiving first information of a candidate target cell from a candidate target network device, the first information including first public land mobile network (PLMN) information and / or first access and mobility management function (AMF) information, and second PLMN information and / or second AMF information; wherein the first information further includes first conditional handover (CHO) configuration information and first area information corresponding to the first PLMN information and / or the first AMF information, and second CHO configuration information and second area information corresponding to the second PLMN information and / or the second AMF information, the first area information being used to indicate a first area covered by the candidate target cell, and the second area information being used to indicate a second area covered by the candidate target cell; Send the first information of the candidate target cell to the terminal device.

24. The method according to claim 23, wherein The first CHO configuration information includes first CHO execution condition information, where the first CHO execution condition information is used to indicate a first CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The first PLMN information includes an identifier of the first PLMN, and the first AMF information includes an identifier of the first AMF, or includes the identifier of the first AMF and an identifier of the first PLMN; The second CHO configuration information includes second CHO execution condition information, where the second CHO execution condition information is used to indicate a second CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The second PLMN information includes the identifier of the second PLMN, and the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

25. A communication method, characterized in that: The method comprises: Sending first information of a candidate target cell to a source network device, the first information including first public land mobile network PLMN information and / or first access and mobility management function AMF information, and second PLMN information and / or second AMF information; wherein the first information also includes first conditional handover CHO configuration information and first area information corresponding to the first PLMN information and / or the first AMF information, and second CHO configuration information and second area information corresponding to the second PLMN information and / or the second AMF information, the first area information being used to indicate a first area covered by the candidate target cell, and the second area information being used to indicate a second area covered by the candidate target cell; If the terminal device determines that the candidate target cell is the target cell, a first message is received from the terminal device, where the first message is used to indicate that the terminal device has successfully switched to the target cell. The first message includes target PLMN information and / or target AMF information, and the target PLMN information and / or the target AMF information is first PLMN information and / or first AMF information, or second PLMN information and / or second AMF information.

26. The method according to claim 25, characterized in that When the random access channel RACH resource information included in the first CHO configuration information is different from the RACH resource information included in the second CHO configuration information, the method further includes: A first key for decrypting the first message is determined based on the RACH resource information used by the terminal device to initiate a random access process, and the first key is used to decrypt the first message.

27. The method according to claim 25, characterized in that When the RACH resource information included in the first CHO configuration information is the same as the RACH resource information included in the second CHO configuration information, receiving a first message from the terminal device includes: receiving two first messages from the terminal device; The two first messages are decrypted using a first key, and / or the two first messages are decrypted using a second key; wherein the first key is a key corresponding to the first CHO configuration information, and the second key is a key corresponding to the second CHO configuration information.

28. The method according to any one of claims 25 to 27, characterized in that The method further comprises: A second message is sent to the target AMF corresponding to the target AMF information, where the second message is used to indicate to the target AMF that the terminal device has completed the switching.

29. The method according to any one of claims 25 to 27, characterized in that The method further comprises: A third message is sent to the AMF corresponding to another AMF information other than the target AMF information in the first AMF information and the second AMF information, where the third message is used to instruct the other AMF to release the connection established for the terminal device.

30. The method according to claim 29, wherein The third message includes a connection release reason value, where the connection release reason value is abnormal location or AMF is unavailable.

31. The method according to claim 28, wherein The method further comprises: A third message is sent to the AMF corresponding to another AMF information other than the target AMF information in the first AMF information and the second AMF information, where the third message is used to instruct the other AMF to release the connection established for the terminal device.

32. The method according to claim 31, characterized in that The third message includes a connection release reason value, where the connection release reason value is abnormal location or AMF is unavailable.

33. The method according to any one of claims 25 to 27 and 30 to 32, characterized in that The first CHO configuration information includes first CHO execution condition information, where the first CHO execution condition information is used to indicate a CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The first PLMN information includes an identifier of the first PLMN, and the first AMF information includes an identifier of the first AMF, or includes the identifier of the first AMF and an identifier of the first PLMN; The second CHO configuration information includes second CHO execution condition information, where the second CHO execution condition information is used to indicate a CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The second PLMN information includes the identifier of the second PLMN, and the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

34. The method according to claim 28, wherein The first CHO configuration information includes first CHO execution condition information, where the first CHO execution condition information is used to indicate a CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The first PLMN information includes an identifier of the first PLMN, and the first AMF information includes an identifier of the first AMF, or includes the identifier of the first AMF and an identifier of the first PLMN; The second CHO configuration information includes second CHO execution condition information, where the second CHO execution condition information is used to indicate a CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The second PLMN information includes the identifier of the second PLMN, and the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

35. The method according to claim 29, wherein The first CHO configuration information includes first CHO execution condition information, where the first CHO execution condition information is used to indicate a CHO execution condition corresponding to the candidate target cell and the first PLMN information and / or the first AMF information, and the first CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The first PLMN information includes an identifier of the first PLMN, and the first AMF information includes an identifier of the first AMF, or includes the identifier of the first AMF and an identifier of the first PLMN; The second CHO configuration information includes second CHO execution condition information, where the second CHO execution condition information is used to indicate a CHO execution condition corresponding to the candidate target cell and the second PLMN information and / or the second AMF information, and the second CHO execution condition information includes one or more of execution condition information based on signal quality, execution condition information based on time / timer, or execution condition information based on location; The second PLMN information includes the identifier of the second PLMN, and the second AMF information includes the identifier of the second AMF, or includes the identifier of the second AMF and the identifier of the second PLMN.

36. A communication device, characterized in that The apparatus comprises a unit for performing the steps of the method according to any one of claims 1 to 22, or a unit for performing the steps of the method according to claim 23 or 24, or a unit for performing the steps of the method according to any one of claims 25 to 35.

37. A communication device, characterized in that: The apparatus comprises at least one processor coupled to at least one memory: The at least one processor is configured to execute a computer program or instruction stored in the at least one memory so that the apparatus performs the method according to any one of claims 1 to 22, or the apparatus performs the method according to claim 23 or 24, or the apparatus performs the method according to any one of claims 25 to 35.

38. A computer-readable storage medium, characterized in that Used to store instructions, which, when executed, enable the method according to any one of claims 1 to 22 to be implemented, or the method according to claim 23 or 24 to be implemented, or the method according to any one of claims 25 to 35 to be implemented.

39. A communication device, characterized in that: including a processor and an interface circuit; The interface circuit is used to exchange code instructions with the processor; The processor is configured to execute the code instructions to perform the method according to any one of claims 1 to 22, or the processor is configured to execute the code instructions to perform the method according to claim 23 or 24, or the processor is configured to execute the code instructions to perform the method according to any one of claims 25 to 35.

40. A computer program product, characterized in that When a computer reads and executes the computer program product, the computer is caused to execute the method according to any one of claims 1 to 22, or the method according to claim 23 or 24, or the method according to any one of claims 25 to 35.

41. A communication system, characterized in that The communication system includes a source network device, a target network device and at least one terminal device, wherein the terminal device is used to implement the method according to any one of claims 1 to 22, the source network device is used to implement the method according to claim 23 or 24, and the target network device is used to implement the method according to any one of claims 25 to 35.

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